The encyclopaedia of arable Weeds Publication Docs/… · The weeds are ordered alphabetically by...

The

encyclopaedia of

arable Weeds

How to use this EncyclopaediaThis publication aims to provide an easy reference to the majorbroad-leaved and grass weeds in the UK including how to identifyand manage them.

The weeds are ordered alphabetically by common names and quick access to a particular weed can also be gained through the Contents which lists weeds both by the common name and the scientific name.

There are two pages of information structured identically for everyweed. A banner provides, at a glance, both the common and thescientific name. Tick boxes identify if the weed is usuallycompetitive in winter wheat, winter oilseed rape and/or springcrops. We have also used tick boxes to show where populationsresistant to herbicides have been identified. Finally, whereappropriate the value of the weed to biodiversity because of rarityvalue, or support to birds or insects, is also indicated.

Each weed has a more detailed description, under the headings;Lifecycle, Location, Description, (including key features andlookalikes), Biology and Management. This is complemented byphotographs of the weed at the different growth stages. A simpleGlossary of terms can be found together with a weed list by EPPOCode at the end of the Encyclopaedia. Where herbicides aresuggested this is to guide the reader to possible options. Beforeapplying herbicides always check product labels for up to daterecommendations and approvals.

This printed encyclopaedia has limited space but there is a lot moreinformation available about all the weeds in this book, and furtherspecies, as well as identification keys in the partner on-line version.The web-based Encyclopaedia of Arable Weeds can be accessed atcereals.ahdb.org.uk/awe .

Cover: Inset pictures from top down: Scarlet pimpernel seedling,black-grass ligule, cornflower seeds, poppy flower and cock’s-foot in cereal crop.

INTRODUCTION 1

IntroductionThis encyclopaedia has been produced to fill the gap that exists in currentlyavailable texts and to provide the reader, in one easy to use format, with a betterunderstanding of weeds, their distribution and biological characteristics togetherwith the best agricultural practice and the impact and importance of both culturaland herbicide use.

It is not a manual on ‘how to do it’, but a source of reference based on anaccumulation of research and information about the weeds, their identification andgrowing habits, to help the reader identify problem weeds and plan their cropmanagement.

Crop production is a competitive balance between crop and weed for light andnutrients. A weed is a plant in an undesired place. It can often grow andreproduce aggressively and/or harbour and spread pests or pathogens which infector degrade the quality of crops. Some can cause skin irritation or are hazardousif eaten. Although many weeds have undesirable consequences they can alsoprovide feed for birds, are attractive to look at or fulfil a key ecological role.

Understanding weeds and their biology enables more effective management.The Encyclopaedia of Arable Weeds provides this in an easily usable format.Supplemented by its on-line partner edition, it provides an essential tool for weedmanagement in arable rotations.

AcknowledgementsThis publication has been substantially based on the encyclopaedia in Weed Manager,which was developed by: ADAS, BASF, Bayer CropScience, Dow AgroSciences,DuPont, AHDB Cereals & Oilseeds, Rothamsted Research, SAC, SRI, and Syngentaunder the Sustainable Arable LINK (Government sponsor Defra); from which the vastmajority of text and images are derived.

We are also very grateful to Susan Jellis (Folia Partners Ltd) for her work on theglossary, editing and advice, and to Sarah Cook (ADAS) for editing texts.

Authors:

James ClarkeADAS

Denise GinsburgADAS

Clare KellyAHDB

Lindy TonguçBASF

CONTENTS2

How to use this guide .................................................. Inside Front CoverIntroduction ............................................................................................ 1

Weeds - Common Name

AAnnual meadow-grass .......................................................................... 12Awned canary-grass ............................................................................. 14

BBarley ................................................................................................... 16Barren brome ....................................................................................... 18Bean, field ............................................................................................ 84Beet, sugar .......................................................................................... 186Bent, black ........................................................................................... 20Bent, creeping ....................................................................................... 66Bent, loose silky ................................................................................. 122Bindweed, black ................................................................................... 22Bindweed, field ..................................................................................... 86Black bent ............................................................................................ 20Black-grass ........................................................................................... 24Black mustard ...................................................................................... 26Black nightshade .................................................................................. 28Black-bindweed .................................................................................... 22Broad-leaved dock ................................................................................ 30Brome, barren ...................................................................................... 18Brome, great ......................................................................................... 98Brome, meadow ................................................................................. 124Brome, rye .......................................................................................... 162Brome, soft ......................................................................................... 180

CCampion, white .................................................................................. 198Canadian fleabane ................................................................................ 32Canary-grass, awned ............................................................................ 14

Contents

CONTENTS Continued

Carrot, wild ....................................................................................... 200Charlock .............................................................................................. 34Chickweed, common ............................................................................ 40Cleavers ............................................................................................... 36Cock’s-foot ........................................................................................... 38Common chickweed ............................................................................. 40Common couch .................................................................................... 42Common field-speedwell ...................................................................... 44Common fumitory ............................................................................... 46Common hemp-nettle ........................................................................... 48Common mouse-ear ............................................................................. 50Common nettle .................................................................................... 52Common orache ................................................................................... 54Common poppy ................................................................................... 56Common vetch ..................................................................................... 58Corn spurrey ........................................................................................ 60Cornflower ........................................................................................... 62Couch, common ................................................................................... 42Couch, onion ..................................................................................... 132Cow parsley ......................................................................................... 64Crane’s-bill, cut-leaved ......................................................................... 74Crane’s-bill, dove’s-foot ........................................................................ 80Creeping bent ....................................................................................... 66Creeping thistle .................................................................................... 68Crested dog’s-tail .................................................................................. 70Curled dock ......................................................................................... 72Cut-leaved crane’s-bill .......................................................................... 74

DDaisy .................................................................................................... 76Dandelion ............................................................................................ 78Dead-nettle, henbit ............................................................................. 108Dead-nettle, red .................................................................................. 152Dock, broad-leaved .............................................................................. 30Dock, curled ......................................................................................... 72Dove’s-foot crane’s-bill ......................................................................... 80

3

CONTENTS Continued4

FFat hen ................................................................................................. 82Fescue, red ......................................................................................... 154Field bean ............................................................................................. 84Field bindweed ..................................................................................... 86Field forget-me-not ............................................................................... 88Field horsetail ....................................................................................... 90Field pansy ........................................................................................... 92Fleabane, canadian ............................................................................... 32Fluellen, round-leaved ........................................................................ 160Fluellen, sharp-leaved ......................................................................... 170Fool’s parsley ....................................................................................... 94Forget-me-not, field .............................................................................. 88Fumitory, common ............................................................................... 46

GGarlic mustard ..................................................................................... 96Great brome ......................................................................................... 98Green field-speedwell ......................................................................... 100Groundsel .......................................................................................... 102

HHedge mustard ................................................................................... 104Hedge-parsley, spreading .................................................................... 184Hemlock ............................................................................................ 106Hemp-nettle, common .......................................................................... 48Henbit dead-nettle .............................................................................. 108Horsetail, field ..................................................................................... 90

IItalian rye-grass .................................................................................. 110Ivy-leaved speedwell ........................................................................... 112

KKnapweed .......................................................................................... 114Knot-grass .......................................................................................... 116

5CONTENTS Continued

LLinseed ............................................................................................... 118Long-headed poppy ............................................................................ 120Loose silky bent ................................................................................. 122

MMayweed, scented .............................................................................. 166Mayweed, scentless ............................................................................ 168Meadow brome .................................................................................. 124Meadow-grass, annual ......................................................................... 12Meadow-grass, rough-stalked ............................................................ 158Mouse-ear, common ............................................................................. 50Mustard, black ..................................................................................... 26Mustard, garlic ..................................................................................... 96Mustard, hedge .................................................................................. 104

NNettle, common ................................................................................... 52Nettle, small ....................................................................................... 176Nightshade, black ................................................................................ 28Nipplewort ......................................................................................... 126

OOat ..................................................................................................... 128Oat, wild ............................................................................................ 202Oat, winter wild ................................................................................. 208Oilseed rape ....................................................................................... 130Onion couch ...................................................................................... 132Orache, common .................................................................................. 54

PPale persicaria .................................................................................... 134Pansy, field ........................................................................................... 92Pansy, wild ......................................................................................... 204Parsley, cow .......................................................................................... 64

CONTENTS Continued6

Parsley, fool’s ........................................................................................ 94Parsley-piert ....................................................................................... 136Pea ..................................................................................................... 138Perennial rye-grass ............................................................................. 140Perennial sow-thistle .......................................................................... 142Persicaria, pale ................................................................................... 134Pineappleweed .................................................................................... 144Pimpernel, scarlet ............................................................................... 164Poppy, common ................................................................................... 56 Poppy, long-headed ............................................................................ 120Potato ................................................................................................ 146Prickly sow-thistle .............................................................................. 148

RRadish, wild ....................................................................................... 206Ragwort ............................................................................................. 150Red dead-nettle .................................................................................. 152Red fescue .......................................................................................... 154Redshank ........................................................................................... 156Rough-stalked meadow-grass ............................................................. 158Round-leaved fluellen ......................................................................... 160Rye brome .......................................................................................... 162Rye-grass, italian ................................................................................ 110Rye-grass, perennial ........................................................................... 140

SScarlet pimpernel ................................................................................ 164Scented mayweed ............................................................................... 166Scentless mayweed ............................................................................. 168Sharp-leaved fluellen .......................................................................... 170Shepherd’s-needle ............................................................................... 172Shepherd’s-purse ................................................................................. 174Small nettle ........................................................................................ 176Smooth, sow-thistle ............................................................................ 178Soft brome ......................................................................................... 180Sow-thistle, perennial ......................................................................... 142

7CONTENTS Continued

Sow-thistle, prickly ............................................................................. 148Sow-thistle, smooth ............................................................................ 178Spear thistle ........................................................................................ 182Speedwell, common field....................................................................... 44Speedwell, green field .......................................................................... 100Speedwell, ivy-leaved .......................................................................... 112Speedwell, wall ................................................................................... 194Spreading hedge-parsley ..................................................................... 184Spurrey, corn ........................................................................................ 60Sugar beet .......................................................................................... 186Sunflower ........................................................................................... 188

TThistle, creeping ................................................................................... 68Thistle, spear ...................................................................................... 182Timothy ............................................................................................. 190

VVenus’s-looking-glass .......................................................................... 192Vetch, common .................................................................................... 58

WWall speedwell ................................................................................... 194Wheat ................................................................................................ 196White campion ................................................................................... 198Wild carrot ......................................................................................... 200Wild-oat ............................................................................................. 202Wild-oat, winter ................................................................................. 208Wild pansy ......................................................................................... 204Wild radish ........................................................................................ 206Winter wild-oat .................................................................................. 208

YYorkshire-fog ..................................................................................... 210

CONTENTS Continued8

Weeds - Scientific Name

AAethusa cynapium ................................................................................ 94Agrostis gigantea .................................................................................. 20Agrostis stolonifera .............................................................................. 66Alliaria petiolata .................................................................................. 96Alopecurus myosuroides ...................................................................... 24Anagallis arvensis ............................................................................... 164Anisantha diandra ................................................................................ 98Anisantha sterilis .................................................................................. 18Anthriscus sylvestris ............................................................................. 64Apera spica-venti ................................................................................ 122Aphanes arvensis ................................................................................ 136Arrhenatherum elatius ........................................................................ 132Atriplex patula ..................................................................................... 54Avena fatua ........................................................................................ 202Avena sativa ....................................................................................... 128Avena sterilis ...................................................................................... 208

BBellis perennis ...................................................................................... 76Beta vulgaris ...................................................................................... 186Brassica napus ssp oleifera ................................................................. 130Brassica nigra ....................................................................................... 26Bromus commutatus .......................................................................... 124Bromus hordeaceus ............................................................................ 180Bromus secalinus ................................................................................ 162Bromus sterilis (see Anisantha sterilis)

CCapsella bursa-pastoris ...................................................................... 174Centaurea cyanus ................................................................................. 62Centaurea nigra .................................................................................. 114Cerastium fontanum ............................................................................ 50Chenopodium album ............................................................................ 82

9CONTENTS Continued

Cirsium arvense .................................................................................... 68Cirsium vulgare .................................................................................. 182Conium maculatum ............................................................................ 106Convolvulus arvensis ............................................................................ 86Conyza canadensis ............................................................................... 32Cynosurus cristatus .............................................................................. 70

DDactylis glomerata ............................................................................... 38Daucus carota .................................................................................... 200

EElytrigia repens .................................................................................... 42Equisetum arvense ............................................................................... 90

FFallopia convolvulus ............................................................................ 22Festuca rubra ..................................................................................... 154Fumaria officinalis ............................................................................... 46

GGaleopsis tetrahit ................................................................................. 48Galium aparine .................................................................................... 36Geranium dissectum ............................................................................. 74Geranium molle ................................................................................... 80

HHelianthus annuus ............................................................................. 188Holcus lanatus ................................................................................... 210Hordeum vulgare ................................................................................. 16

KKickxia elatine ................................................................................... 170Kickxia spuria .................................................................................... 160

CONTENTS Continued10

LLamium amplexicaule ........................................................................ 108Lamium purpureum ........................................................................... 152Lapsana communis ............................................................................ 126Legousia hybrida ................................................................................ 192Linum usitatissimum .......................................................................... 118Lolium multiflorum ........................................................................... 110Lolium perenne .................................................................................. 140

MMatricaria discoidea ........................................................................... 144Matricaria recutita ............................................................................. 166Myosotis arvensis ................................................................................. 88

PPapaver dubium ................................................................................. 120Papaver rhoeas ..................................................................................... 56Persicaria lapathifolia ......................................................................... 134Persicaria maculosa ............................................................................ 156Phalaris paradoxa ................................................................................ 14Phleum pratense ................................................................................. 190Pisum sativum .................................................................................... 138Poa annua ............................................................................................ 12Poa trivialis ........................................................................................ 158Polygonum aviculare .......................................................................... 116

RRaphanus raphanistrum ..................................................................... 206Rumex crispus ...................................................................................... 72Rumex obtusifolius .............................................................................. 30

SScandix pecten-veneris ....................................................................... 172Senecio jacobaea ................................................................................ 150Senecio vulgaris .................................................................................. 102Silene latifolia ..................................................................................... 198

11CONTENTS Continued

Sinapis arvensis .................................................................................... 34Sisymbrium officinale ......................................................................... 104Solanum nigrum ................................................................................... 28Solanum tuberosum ........................................................................... 146Sonchus arvensis ................................................................................ 142Sonchus asper ..................................................................................... 148Sonchus oleraceus .............................................................................. 178Spergula arvensis .................................................................................. 60Stellaria media ...................................................................................... 40

TTaraxacum agg. .................................................................................... 78Torilis arvensis ................................................................................... 184Tripleurospermum inodorum ............................................................. 168Triticum aestivum .............................................................................. 196

UUrtica dioica ........................................................................................ 52Urtica urens ....................................................................................... 176

VVeronica agrestis ................................................................................ 100Veronica arvensis ............................................................................... 194Veronica hederifolia ........................................................................... 112Veronica persica ................................................................................... 44Vicia faba ............................................................................................. 84Vicia sativa ........................................................................................... 58Viola arvensis ....................................................................................... 92Viola tricolor ...................................................................................... 204

Weed list by EPPO code ...................................................................... 212

Glossary ............................................................................................. 216

Reference material and further reading ............................................. 224

Geographic locationAnnual meadow-grass growsnationwide and up to an altitudeof 1200m.

Soil typeIt prefers fertile, heavily disturbedsoils.

ANNUAL MEADOW-GRASS

Annual meadow-grassPoa annua

Value to BiodiversityResistanceSpring CropsWOSR� �

WW

12

Seed longevity: >5 years

Seed weight: 0.2 mg

Seeds/flower: 1

Seeds/plant: 10 - 500

seed Shed

flowering

germination

Lifecycle

Not present More likely

Unlikely Very likely

seed shed

flowering

germination

Location

Competitive in

13ANNUAL MEADOW-GRASS

DescriptionIt is a tufted annual or short-lived perennialgrass, often compact, 3 - 30cm tall. Shootsand leaves appear flattened. The flowers forman open pyramid on the shoot.

Key FeaturesYoung plant: The leaves are light green andflattened, with a curved tip; the undersideshave a distinctive central ridge.

Flowers: It flowers all year round.

BiologyAnnual meadow-grass is the most common grass weed in winter- and summer-sown arablecrops throughout most of the UK. As it canoverwinter, plants are found at all growth stagesduring the year. It can complete its lifecycle in 6weeks. Although most reproduction is by seed,annual meadow-grass has long lateral roots andcan also regenerate from shoots detached fromthe main plant by disturbance.

Annual meadow-grass poses little threat tocrop yield, but can delay ripening andinterfere with harvest.

ManagementIt is encouraged by minimum tillagecompared to ploughing. Residual herbicidescontrol it both in cereals and other crops.It has developed resistance to some herbicides:paraquat in hops and simazine in orchards.

Scale: 1 space = 1mm

AWNED CANARY-GRASS

Awned canary-grassPhalaris paradoxa

Value to BiodiversityResistance

Competitive in

Spring CropsWOSR� �WW

14

Geographic locationAwned canary-grass is a lowlandweed, especially in south Britain.

Soil typeIt likes moisture-retentive soils.

Seed weight: 1.25 mg

Lifecycle



Location

seed shed

flowering

germination

unknown

15AWNED CANARY-GRASS

DescriptionIt is a tufted annual grass up to 1m tall, freelytillering, with long tapering leaves and a longpointed ligule. The flowerheads are upright,broad and densely packed with spikeletswhich have green and white striped markings.

Key features Flowers/fruit: The flowerheads fall intactwhen ripe.

BiologyAwned canary-grass is an annual grass whichonly reproduces by seed. Although it isuncommon, it is a fairly new but increasingproblem. It is generally found in the sameareas as black-grass, in moisture-retentivesoils. It is competitive with cereal crops. It spreads initially from volunteers of previousbird-seed crops. It is difficult to control withthe usual grass herbicides and can be a seriousweed in winter crops.

ManagementSeeds may be buried by deep ploughing, andleaving in the seedbank for 2 – 3 years.Cycloxydim may be used in some broad-leaved crops.


BARLEY

BarleyHordeum vulgare


Competitive in

Spring CropsWOSRWW

16

Geographic locationWinter and spring barleys arefound as weeds in lowland areas,on road verges and wasteland, aswell as in cereal crops.

Soil typeWeed barleys are found on all soiltypes, though are less common insoils under organic management.

Seed longevity: <1 year

Seed weight: 58 mg

Seeds/ear: 19 - 25


Lifecycle



seed shed

flowering

germination

Location

17BARLEY

DescriptionBarley is a tufted grass 60 - 120cm tall, withfew leaves.

Key features Young plant: The leaf blades are hairlessand yellow-green, with a clockwise twist.

Flowers/fruit: The nodding flowerheadshave very long awns.

BiologyBarley volunteers from the previous crop cangerminate after harvest if soil conditions arefavourable. The young plants persistoverwinter and will flower before thefollowing wheat crop. However, they seldompersist in the seedbank beyond 2 years ifcontrolled. Barley is a particular nuisance asa weed in cereal seed crops, and in millingand processing crops.

ManagementIt can be controlled with herbicides in broad-leaved crops and, with certain grassherbicides, in wheat.


BARREN BROME

Barren bromeAnisantha sterilis


Competitive in

Spring CropsWOSR�

WW

18

Geographic locationFound mainly in England and thearable areas of Scotland, barrenbrome is usually a lowland grass,but has been shown to reachaltitudes of over 350m. Its naturalhabitat includes verges, fieldheadlands and waste ground.

Soil typeIt grows on waste or cultivatedland on well-drained soils.

Seed longevity: 1 - 5 years

Seed decline: 90% per year

Germination depth: 5 cm

Seed weight: 8.4 mg

Seeds/flower: 1

Seeds/plant: 200

Lifecycle



seed shed

flowering

germination

�

Location

19BARREN BROME

DescriptionIt is an annual tufted grass that can grow to 100cm in height. The leaf blades are green, turningpurple, and are finely pointed and covered inshort hairs. It is also known as sterile brome.

Key featuresPlant: The ligule is very pointed.Flower: The long-awned droopingflowerhead is tinged with purple afterflowering.

BiologyBarren brome is a weed of winter crops,causing lodging when present in largepopulations. Plants overwinter with greenleaves; seeds germinate mainly in autumn.Spring-germinating seedlings can flower thesame year. Population increase is favoured bycereal monoculture, early-autumn cerealsowing, no-till cultivation and lack of breakcrops. Seed germination is inhibited bydrought and by low temperatures aftershedding. Barren brome can be verycompetitive in the early stages of crop growthof autumn-sown cereals, particularly wherethe crop is established by reduced cultivations.

ManagementSeed dormancy varies between populationsbut is lost rapidly. Seed burial can inducedormancy. Seed should be left on the soilsurface as light aids germination. Withminimum cultivations, move the seeds intodamp positions to encourage germination.Spray off with glyphosate prior to drilling.

Barren brome is unlikely to emerge from adepth >10cm so deep ploughing to 15cmimmediately after harvest helps control.


BLACK BENT

Black bentAgrostis gigantea


Competitive in

Spring CropsWOSRWW

20

Geographic locationBlack bent is mainly found inarable fields in lowland areas ofEngland, the arable areas ofScotland and locally in Ireland.

Soil typeIt spreads in light sandy soils whereit reproduces both from rhizomesand from seed. In wetter soils it canpropagate only from rhizomes.



Lifecycle



seed shed

flowering

germination

Location

21BLACK BENT

DescriptionIt is a loosely tufted perennial grass that cangrow to a height of 40 - 120cm.It has tough creeping rhizomes.

Key features Plant: The leaves are dull, green andhairless; the blades are flat, broad and taperto a point; the sheaths are rounded andsmooth.

Flowers: The large green or purplishflowerheads are upright, oval and usuallyopen, with many branches carrying single-flowered spikelets.

LookalikesBlack bent may be confused with creepingbent.

BiologyBlack bent can develop into dense patcheswhich are often a problem in fields that arefrequently irrigated and where weather iscool. The plants can reproduce vegetativelyfrom fragments of rhizome.

ManagementSpring cropping reduces vigour. Whencultivating, beware of breaking the rhizomesas black bent can root from every brokennode. Glyphosate used in summer onuncropped land or pre-harvest in earlyharvested crops controls rhizomes. Someresidual herbicides may affect the seedlings.


BLACK-BINDWEED

Black-bindweedFallopia convolvulus


Competitive in

Spring CropsWOSR� �

WW

22

Geographic locationBlack-bindweed is mainly found inlowland areas but can grow up toan altitude of 400m, in arable,especially cereal crops, disturbedland, other bare ground and roadsides.

Soil typeIt grows on fertile, moist soils withpH >5.


Seed weight: 5mg


Lifecycle



seed shed

flowering

germination

Location

23BLACK-BINDWEED

DescriptionIt is a summer annual that scrambles as highas the supporting vegetation will allow.The flowers grow on loose flowering spikes.

Key featuresSeedling: The hypocotyl is crimson and thecotyledons and first leaves reddish.

Plant: Although the leaves are heart-shapedand resemble field bindweed, the lowerlobes of black-bindweed leaves are morerounded than those of field bindweed.

LookalikesYoung plants of black-bindweed can beconfused with those of field bindweed.The difference is in the cotyledons;black-bindweed has long cotyledons withshort stalks, while field bindweed has ovalcotyledons, notched at the tip.

BiologyBlack-bindweed is one of the most commonweeds of cereals; it occurs particularly inspring cereals and in open crops of winterwheat. It is also found in potato, beet andmaize crops. It grows rapidly from largeseedlings mainly germinating in spring and isdeep rooting. Seeds are dispersed in cerealgrains. Plants germinating in autumn do notsurvive winter.

ManagementIn cereals, combinations of sulfonylureas andhormonal and contact herbicides are oftenneeded for good control. In spring broad-leaved crops and maize, control can bevariable if soil conditions are dry and residualherbicides do not work well.


BLACK-GRASS

Black-grassAlopecurus myosuroides


Competitive in

Spring CropsWOSR� � �WW

24

Geographic locationBlack-grass is most abundant incultivated land in south-eastEngland, but it is distributed allover the British Isles. It hasgradually spread north and west,recently appearing in south-eastScotland and Northumberland, butis still rare in northern Scotland.

Soil typeIt is found on heavy and light soils,but thrives on heavy, poorlydrained soils.



Germination depth: 5.7 cm

Seed weight: 1.8 mg

Seeds/head: 100

Seeds/plant: 800

Lifecycle



seed shed

flowering

germination

Location

25BLACK-GRASS

DescriptionIt is an annual grass, 20 - 85cm tall with upright,round and slender stems which have few nodes.Black-grass grows in graceful tufts. The verynarrow, dark purple flowerhead is packed withsingle-flowered spikelets.

Key featuresYoung plant: The leaves are fine and smooth witha shiny upper surface; the leaf blade is twistedwith a blunt tip. The lower sheath of largerseedlings is often purple.

LookalikesBlack-grass can be confused with loose silky bentat the young plant stage of development, due to thereddish/purple colouring of the leaf sheath, butsilky-bent tends to prefer lighter soils.

Biology Black-grass is a major weed of winter-sown cerealswith very high seed production. Crop profit isreduced because of yield loss, herbicide cost anddelayed sowing. Seeds produced in high numbersare shed before crop harvest. About 80% willgerminate in winter and these tiller in early spring.Black-grass can emerge from clods broken downduring winter. There is very little spring emergencefrom undisturbed soils.

ManagementPloughing buries new seed but older seed broughtto the soil surface may germinate. Some 80% of theburied seed dies in the first year. Restrictingploughing to alternate years minimises old seedfrom being ploughed up. Stale seedbeds and delayeddrilling allow more time for black-grass to emergeand be sprayed off with a non-selective herbicidebefore drilling.

There is a high risk of herbicide resistancedeveloping if ‘fop’, ‘dim’ or ALS herbicides are usedrepeatedly. It is best to control black-grass in breakcrops, as the different herbicide groups used withbroad-leaved crops reduce the risk of resistancedevelopment. Spring-sown crops can also help.


BLACK MUSTARD

Black mustardBrassica nigra


Competitive in

Spring CropsWOSR�

WW

26

Geographic locationGenerally a lowland plant, blackmustard grows persistently nearrivers, in flood plains, in arablefield margins and in waste ground.

Soil typeIt prefers nutrient-rich and dampclays and silts.




Lifecycle



seed shed

flowering

germination

Location

unknown

27BLACK MUSTARD

DescriptionIt is a tall, branched, annual dicotyledon,40-200cm tall with a bristly lower stem. The flowers are bright yellow.

Key featuresLeaves: The leaves are lobed and hairy.

Biology Black mustard was formerly cultivated asmustard seed, though it is now rarely grown.Although some early-germinating plantsoverwinter they are not hardy and seldomsurvive the winter, so seed germinating inspring is more of a problem in late-sownwheat and spring-sown crops.

ManagementUse a stale seedbed approach before sowingspring crops. Control seedlings with harrowsand established plants with hoeing. Blackmustard can be controlled with foliar-actingherbicides.


BLACK NIGHTSHADE

Black nightshadeSolanum nigrum


Competitive in

Spring CropsWOSR� �

WW

28

Geographic locationBlack nightshade is fairlywidespread in vegetable crops,gardens, vineyards and on banksand rubbish tips.

Soil typeIt prefers loose, free-draining,nutrient-rich soils in the pH range5 to 7.



Seed weight: 1 mg

Seeds/flower: 40

Seeds/plant: 500

Lifecycle



seed shed

flowering

germination

Location

29BLACK NIGHTSHADE

DescriptionIt is a branched, bushy annual plant withdark oval leaves, growing up to 70cm tall.The flowers resemble white potato flowersand occur in groups of 5 to 10.

Key featuresYoung plant: The hypocotyls and cotyledonsare hairy.

Fruit: The fruit is spherical andglossy black.

Biology Black nightshade is a locally common weed of vegetable and spring legume crops. Flowers are pollinated by insects and self-fertile. It germinates in spring and summer,fruiting in the same year. The seeds aredistrubuted by birds. It does not persist inwinter crop rotations and where there arelarge grass breaks.

ManagementThere are a number of herbicides available tocontrol black nightshade in winter wheat butit is easier to control the weed in uncroppedland. In row crops, use hoes where herbicidesare not available.

Biotypes resistant to simazine have beenfound in the UK.


BROAD-LEAVED DOCK

Broad-leaved dockRumex obtusifolius


Competitive in

Spring CropsWOSR�

WW

30

Geographic locationBroad-leaved dock grows inmeadows, pastures, ditches, wasteground and neglected cultivatedground up to an altitude of 850m.

Soil typeIt prefers high-nitrogen, humus-richclay or loam soils.




Seeds/flower: 1

Seeds/plant: 7000

Lifecycle



seed shed

flowering

germination

Location

31BROAD-LEAVED DOCK

DescriptionIt is an upright perennial with a long tap root,branched stems and sturdy broad leaves. The flower spike may be branched withclusters of flowers spaced apart.

Key featuresLeaves: The blades of the first true leavesare broad, rounded at the tip and heart-shaped at the base.

Flowers: The margins of the flowers aretoothed.

Fruit: The segments have spiny teeth.

Biology Broad-leaved dock occurs more rarely onarable land than does curled dock, withwhich it is able to hybridise. It tends to growin compacted and damp soil around fieldedges and in gateways. It overwinters as arosette, flowering in the second year. It canreproduce from root fragments detached byploughing.

ManagementBroad-leaved dock can be controlled withherbicides in cereals, grass and uncroppedland, but can be difficult to control in othercrops except by pulling or hoeing.


CANADIAN FLEABANE

Canadian FleabaneConyza canadensis

Value to BiodiversityResistanceSpring CropsWOSRWW

32

Geographic locationCanadian fleabane is a plant ofopen lowland habitats such asgardens, waste ground, railwayballast and urban areas.

Soil typeIt grows on rough, stony, sandy ordrained loam soils with somenitrogen.


Seeds/flower: 45

Seeds/plant: 0 - 50 000



Location

Lifecycle

Competitive in

seed shed

flowering

germination

33CANADIAN FLEABANE

DescriptionIt is an upright, branched annual dicotyledon,growing up to 180cm tall. The plantgerminates in winter and overwinters as asmall rosette of long hairy leaves, sometimeswith toothed edges, from which the floweringstem grows during late spring. Small daisy-like flowers with upward-pointing petals aretightly enclosed by the sepals, and occur inloose flower spikes.

LookalikesCanadian fleabane may be confused withdaisy which is similar in the seedling stage,but has more-rounded cotyledons.Field forget-me-not is similar at the seedlingstage, but has hairy cotyledons.

BiologyCanadian fleabane only occurs sporadicallybut increasingly in annual arable andvegetable crops, e.g. carrot and parsnip.

ManagementThe rosettes can be destroyed by autumncultivations.


CHARLOCK

CharlockSinapis arvensis

Value to BiodiversityResistanceSpring CropsWOSR� � �WW

34

Geographic locationCharlock is generally a weed oflowland areas though it has beenfound at altitudes up to 450m.It grows in open habitats, such asarable fields or recently disturbedsoils.

Soil typeIt is found on well-aerated andwell-watered but drained, alkaline-rich soils, which have a highorganic matter content.



Seed weight: 2 mg

Seeds/flower: 8 - 13




Location

Lifecycle

Competitive in

seed shed

flowering

germination

35CHARLOCK

DescriptionCharlock is a 20 - 200cm high, dark-green topurplish hairy annual; it can be very variablein form, with irregularly toothed leaves.The pale yellow four-petalled flowers occur atthe top of the flowering spike.

Key featuresFlowers: The flower sepals spreadhorizontally.

Fruit: The fruit has a beak 7mm or morelong.

BiologyCharlock is common on arable land. It usedto be a serious weed of cereals, but it is nowmore commonly found in broad-leaved crops.It is highly competitive in cereals. It mainlygerminates in spring, but summer-germinatingplants and plants emerging in the autumn inearly-sown oilseed rape may survive a mildwinter. The seeds can be dispersed in cropseeds, or by ingestion by birds.

ManagementCharlock is difficult to control in brassicacrops but is readily controlled by residual andfoliar herbicides in cereal and legume crops.Between 4 and 6 weeks after germinating, itshairy leaf surface traps herbicide so it is moresusceptible at this stage.


CLEAVERS

CleaversGalium aparine

Value to BiodiversityResistanceSpring CropsWOSR� �WW

36

Geographic locationCleavers is found all over Britainexcept for the very highestmountainous areas. It has spreadnorth and west following the trendsin winter cropping.

Soil typeIt is found on well-watered humus-rich loam and clay soils and growsbest on highly fertile soils.



Seed weight: 8.3 mg

Seeds/flower: 2




Location

Lifecycle

Competitive in

seed shed

flowering

germination

37CLEAVERS

DescriptionIt is a scrambling or climbing annual dicotyledon.The stems are four-angled, 50 - 200cm long,covered with minute, down-curved prickly hairs.

Key featuresYoung plant: The oval cotyledons are notchedat the tip.

Flowers: The flowers are white.

LookalikesCleavers may be confused with ivy-leavedspeedwell at the cotyledon stage. Cleavercotyledons are notched at the tip and havelonger cotyledon stalks. Cleavers may also beconfused with some hemp-nettles.

BiologyCleavers can germinate and young plants continueto grow over mild winters, although mature plantsdie before frost starts. Adult cleavers plants arevery competitive; they can be very large and canchoke wheat crops by growing over the top of thecanopy, causing crop lodging and affectingcombining. Seeds are moved in crop grain or byclinging to fur or clothing and require chillingbefore germination. A long autumn germinationperiod is supported in a winter cropping system.3% of oilseed rape samples are rejected becausethey contain more than 4% of cleavers seed. Theseeds can also be difficult to remove from cerealsamples and cause losses of grain.

ManagementCleavers cannot be controlled purely by culturalmethods. Mechanical and tine weeders can be usedto remove a proportion of emerged cleavers withinthe wheat crop. Ploughing may increase seedlingemergence, when seeds brought to the soil surfacegerminate. There are a number of herbicides thatcan be used to control cleavers in arable crops.


COCK’S-FOOT

Cock’s-footDactylis glomerata

Value to BiodiversityResistanceSpring CropsWOSR�

WW

38

Geographic locationCock’s-foot is usually found inmeadows, pastures, waste ground,roadsides, or field edges. It growsto an altitude of 700m.

Soil typeIt is found on a wide range offertile, neutral or alkaline soils.


Seed weight: 2 mg

Seeds/head: 100



Location

Lifecycle

Competitive in

seed shed

flowering

germination

39COCK’S-FOOT

DescriptionIt is a large, densely tufted, perennial grass ofcoarse appearance, 30cm to 1.2m tall. Thereare many strains, with differing growthhabits. The broad leaf blades have aprominent ridge on the undersides and areoften bluish-green in colour. The flowerheadsare often triangular and appear denselypacked.

Key featuresPlant: The stems are flattened, especially atthe base.

BiologyCock’s-foot is sown as an agricultural grassand may be present in arable fields afterploughing. It remains green all winter. It mainly reproduces by seed which canpersist from 2 to 3 years on the soil surface.Seed set is high and the fruit fairly mobile.

ManagementAlthough it is often found in first-year cerealsafter grass, it seldom persists in routinelycultivated soils. It is best controlled at thetime of grass destruction or in fallow.


COMMON CHICKWEED

Common chickweedStellaria media

Value to BiodiversityResistanceSpring CropsWOSR� � � �

WW

40

Geographic locationCommon chickweed can be foundall over Britain, especially in crops,usually below an altitude of 200mbut able to grow up to 400m.

Soil typeIt grows on fertile nitrogen-richsoils which are not highly acid.It prefers watered but notwaterlogged situations.




Seeds/flower: 8

Seeds/plant: 2500



Location

Lifecycle

Competitive in

seed shed

flowering

germination

41COMMON CHICKWEED

DescriptionIt is an annual low-growing bright-greenplant, with tiny five-petalled white flowers.

Key featuresPlant: The stems are rounded with a singleline of hairs.

Leaves: The leaves are oval, usually 8mmor longer, and end in a slight point.

LookalikesCommon chickweed may be confused withcommon mouse-ear.

BiologyCommon chickweed can grow at relativelylow temperatures and may suppressoverwintered crops or, if dense, severelyrestrict crop growth. Germination ofchickweed can occur throughout the year,with up to three generations possible in anyone year in winter cereals, particularly wheat;plants may be seen to be flowering at anytime. Spring-germinating plants die in latesummer, while autumn-germinating plantssurvive the winter as a dense low-growingmat. Plants may reproduce by seed, moved bybirds, or vegetatively by root cuttings.

ManagementControl by preventing seed production and re-establishment after cultivation. Early shallowtillage encourages the seed germination; whenthe seedlings emerge, the land should be tilledagain and then drilled with the crop.

Sulfonylurea resistance in chickweed has beenconfirmed in the UK. Where sulfonylureaherbicides are used, mix with a herbicide withan alternative mode of action.


COMMON COUCH

Common couchElytrigia repens


42

Geographic locationCouch grows country-wide onfertile disturbed soils, waste andcultivated ground up to an altitudeof 430m.

Soil typeIt is present on all soil typesincluding seaside sands andshingles.

Seed longevity: 1-5 years

Seed weight: 2.5 mg

Seeds/head: 100




Location

Lifecycle

Competitive in

seed shed

flowering

germination

43COMMON COUCH

DescriptionIt is a tall, very vigorous perennial grass up to20cm with white, creeping undergroundrhizomes growing into large groups orpatches. The leaves are hairy on the innersurface and rough at the edges. Spikelets arearranged in two opposite rows.

Key featuresPlant: As the rhizome extends, commoncouch plantlets seem to grow in straightlines. The individual plants have an uprightform.

Flower: Spikelets lie flat against the stem sothey feel smooth when fingers are movedalong the flowerhead.

LookalikesThe flowerhead is superficially similar tothat of rye-grass (Lolium spp.) but in rye-grass the narrow, rounded side of thespikelet is adjacent to the stem.

BiologyCommon couch is a highly competitive weedof all crops. Mature shoots die back in theautumn but young shoots can overwinter.The plant can reproduce from rhizomefragments and from seed.

ManagementIntensive cultivations at 2 - 3 week intervalswill fragment the rhizomes and inducegrowth, exhausting food reserves. Bury theweakened rhizomes with deep ploughing orspray with glyphosate. Control of couch ischeaper and more effective with glyphosate inuncropped land, stale seedbeds or combinablecrops than in break crops.


COMMON FIELD-SPEEDWELL

Common field-speedwellVeronica persica


WW

44

Geographic locationCommon field-speedwell grows upto an altitude of 350m and prefersflat or gently sloping ground. It is acommon weed of arable land andother bare soils such as disturbed orwaste ground.

Soil typeIt prefers damp, nutrient-rich loamsoils, pH 6 to 8.



Seeds/flower: 7




Location

Lifecycle

Competitive in

seed shed

flowering

germination

45COMMON FIELD-SPEEDWELL

DescriptionIt is a low sprawling hairy annual with asturdy stem, forming loose cushions 10 -40cm across. The leaves are broadlytriangular and toothed, on short stalks. The large flowers, 9 - 14mm are borne onlong stalks growing from the leaf axils; theupper petals are sky blue and the lower white.

Key featuresFlower: Flowers are large and predominantlysky blue.

BiologyCommon field-speedwell is frequently foundon arable land, both on fallow ground andbeneath the crop canopy. It is found onautumn- and spring-sown crops probablyencouraged by an increase in winter cropping.Plants can overwinter and even flowerthroughout the year, giving rise to twogenerations per season; the large seeds areprobably dispersed by ants. Shoot fragmentsare able to regenerate.

ManagementResidual herbicides are generally quiteeffective in autumn- and spring-sown crops;sulfonylureas and contact herbicides areeffective in cereals.


COMMON FUMITORY

Common fumitoryFumaria officinalis


WW

46

Geographic locationCommon fumitory is a lowlandplant, growing up to an altitude of300m. It appears in winter andspring crops and may be increasingin fields of winter cereals in thenorth of England and in Scotlandwhere there is poor control byresidual herbicides.

Soil typeIt prefers nutrient-rich chalky loamswith good water availability and isan indicator of good soilconditions.


Seed weight: 4 mg

Seeds/flower: 1

Seeds/plant: 1600



Location

Lifecycle

Competitive in

seed shed

flowering

germination

47COMMON FUMITORY

DescriptionIt is a slender, hairless, semi-upright orsprawling, branched annual dicotyledon,growing up to 40cm tall. The smooth leavesare divided, feathery and slightly greyish incolour. The flower stems have many pinkishlipped flowers, 7 - 8mm long and tipped withdark purple-red.

Key featuresPlant: The sap is colourless.Flower: The sepal is less than half theflower length. There are often more than 20flowers on a flowering spike.

Fruit: It is shaped like a flattened globe.

BiologyCommon fumitory is widespread on arableland. It mainly germinates in spring and canset seed in one year. It can be self-fertile orcan cross-fertilise.

ManagementControl of established plants is difficult withherbicides. Seedlings can be controlled withmecoprop-P and HBN herbicides in cereals.


COMMON HEMP-NETTLE

Common hemp-nettleGaleopsis tetrahit


WW

48

Geographic locationCommon hemp-nettle occurs indisturbed ground with high levels ofbare soil, often in broad-leavedcrops, or in moist sites near riverbanks and hedgerows, up to analtitude of 400m. It commonlyoccurs in spring cereals in northernEngland and Scotland.

Soil typeIt can grow on a wide range of soilspH 4.5 - 7, and may be morecommon in soils of relatively highorganic matter or in areas wheresoils remain moist in the summer.



Seeds/flower: 4




Location

Lifecycle

Competitive in

seed shed

flowering

germination

49COMMON HEMP-NETTLE

DescriptionIt is a bristly annual dicotyledon, with leavesresembling those of common nettle.The stems are brittle and usually have distinctswellings below the attachment of each leaf-pair. The flowers are cream or pink andsimilar to those of dead nettle.

Key featuresPlant: There is a distinct swelling where theleaf stalk meets the stem. Plants can have abristly appearance.

BiologyCommon hemp-nettle forms more robustplants in broad-leaved crops and fallowground than in cereal crops. The plantsreproduce by seed, which is produced insmaller quantities than in similar plants andmay still be on the plant during harvest, socontaminating crop grain. Seeds germinateonly after overwintering.

ManagementIt is controlled by a range of broad-leavedweed herbicides.


COMMON MOUSE-EAR

Common mouse-earCerastium fontanum


WW

50

Geographic locationCommon mouse-ear grows toaltitudes of above 1000m in allareas of Britain, in fertile habitatsincluding meadows, pastures,cultivated ground, dunes andshingle.

Soil typeIt likes acidic, wetter soils, rich innutrients.


Seed weight: 0.1 mg

Seeds/flower: 40




Location

Lifecycle

Competitive in

seed shed

flowering

germination

51COMMON MOUSE-EAR

DescriptionIt is a sprawling or upright, perennialdicotyledon 5 - 50cm tall. The small ovalleaves and the stem are covered with densewhite hairs. The flowers have five whitepetals, with sepals the same length as thepetals.

Key featuresYoung plant: The seedlings are very smalland hairy.

BiologyCommon mouse-ear is a perennial, whichfunctions as an annual in arable fields.The seeds are dispersed by wind or eaten bybirds. It can emerge throughout the year,given sufficient soil moisture.

ManagementIt is less common where soils are routinelycultivated and is likely to be encouraged byreduced cultivation and direct drilling. It doesnot compete in dense, vigorous crops.


COMMON NETTLE

Common nettleUrtica dioica


WW

52

Geographic locationCommon nettle is found in a widevariety of habitats includingcultivated and waste ground, scrub,unmanaged grassland, and fen andriver banks, up to an altitude of850m.

Soil typeIt prefers nutrient-rich soils.



Seeds/flower: 1



Location

Lifecycle

Competitive in

seed shed

flowering

germination

53COMMON NETTLE

DescriptionThis common hedgerow perennial grows toabove 1.5m and has extensive creepingrooting stolons. The leaves are pointed withtoothed edges. The stem is square in crosssection and covered with stinging hairs. The tiny green male and female flowers areborne in tassels by different plants.

Key featuresYoung plant: It has longer and moretriangular first true leaves than annualnettle.

Plant: It is tall and upright, with leaveslarger than those of small nettle. The leavesand stem are covered in stinging hairs.

LookalikesCommon nettle may be confused with smallnettle, however it has shorter cotyledonsthan small nettle and the first true leaves ofcommon nettle are longer and moretriangular.

BiologyCommon nettle is frequently found in wasteplaces and field margins, though it doesencroach onto arable land. It is a particularproblem in perennial crops and grassland.Some young shoots of nettle can overwinter,but the plant mostly dies back, growingstrongly in spring. The plants reproduce whenstolons are fragmented or from seed ingestedby animals.

ManagementIt will be reduced by continuous cutting. For control, use glyphosate in fallow orselective treatments in grassland.


COMMON ORACHE

Common oracheAtriplex patula


WW

54

Geographic locationCommon orache is mainly alowland weed but can grow up toan altitude of 400m. It is found onarable land, on manure heaps,demolition sites, and areas with alarge amount of bare soil.

Soil typeIt prefers moist soils with pH > 5.


Seed weight: 2 mg




Location

Lifecycle

Competitive in

seed shed

flowering

germination

55COMMON ORACHE

DescriptionIt is a sturdy annual plant, growing up to80cm tall. It has a branched stem and long,horizontally spreading branches. Leaves areinitially mealy, later turning green on bothsides. Flowers form in small clusters along theflowering stalk, the female flowers arepyramid-shaped.

Key featuresPlant: The young leaves are mealy.The shoots of the growing plants haveupright triangular leaves at the top.

LookalikesCommon orache may be confused with fat-hen: fat-hen and Good King Henry alsohave mealy leaves. Orache has broadercotyledon stalks with leaf and cotyledonhaving a bright-green underside, whilstyoung fat-hen plants may be bright purpleon the underside of the cotyledons.

BiologyCommon orache is particularly common inbroad-leaved crops or fallow areas. Plantsregenerate only by seed, which can be animpurity in crop seed, and may be spread bybirds or small mammals. The plants do notoverwinter. Early sown winter crops are usuallytoo competitive to be affected by this spring-germinating species but the deep tap root caninterfere with harvesting of beet crops.

ManagementMinimum tillage may reduce emergence.It can be controlled by a range of herbicidesat the seedling stage.


COMMON POPPY

Common poppyPapaver rhoeas

Value to BiodiversityResistanceSpring CropsWOSR� � �

WW

56

Geographic locationPoppy is widely distributed in allareas of the British Isles, but is lessabundant in northern Scotland. Ittends to prefer lowland areas.

Soil typePoppy prefers soils with reasonablemoisture and will spread in areaswith bare soil.

Seed longevity: Up to 100 years



Seeds/flower: 1360

Seeds/plant: 20 000



Location

Lifecycle

Competitive in

seed shed

flowering

germination

57COMMON POPPY

DescriptionIt is an upright, hairy annual 20-80cm tall.The stems are bristly and sometimes spreading.The dull green leaves at the base form a rosettewith divided segments. The broken stem bleedsa white sap. The large flowers have four petalssometimes with a large black spot at the centre.The ovary is short and smooth.

Key featuresFruit: The seed head is short and smooth.

LookalikesCommon poppy may be confused withyoung plants of shepherd’s-purse but thecotyledons of common poppy are narrower.The hairs of the common poppy stand singlyand may be forked, while those of shepherd’s-purse form little star-like clusters.

BiologyCommon poppy occurs particularly in wintercereals and oilseed rape where it is competitive,but is also found in spring crops, fallows andmore rarely vegetables and clover crops.Autumn-germinating seedlings can overwinter.Plants flower in midsummer, but there may be asecond flush of flowers once the wheat crop hasbeen harvested. The plant reproduces entirelyby seed. The very long seed persistence meansthat poppy appears in newly cultivated land.

ManagementThe best control method is to stimulategermination through cultivation before sprayingwith glyphosate. Common poppy is controlled bya wide range of herbicides in cereals and legumes,but control is more difficult in brassicae crops.

Sulfonylurea resistance has been confirmed inthe UK.


COMMON VETCH

Common vetchVicia sativa


WW

58

Geographic locationAlthough it is widely found inlowland areas in most of the BritishIsles, in Ireland it is mainlyconfined to the east coast.

Soil typeIt prefers dry and sandy soils.


Seed weight: 100 mg




Lifecycle

Location

Competitive in

seed shed

flowering

germination

59COMMON VETCH

DescriptionA scrambling dicotyledon, the stems grow to20 - 120cm in length. The leaves are dividedinto 3 to 8 pairs of oval leaflets and end in atendril. The flowers are like those of a peaand occur in the last few leaf axils.

Key featuresYoung plant: The first true leaves arelong and narrow with no leaflets.

BiologyCommon vetch was once grown as acultivated plant. It is found in grassy fieldmargins, but may also be seen in arable crops,sometimes as cultivated forms where vetchesform part of the cropping rotation. Commonvetch usually germinates in autumn andoverwinters; more rarely it is a summerannual. Undisturbed plants may be biennial.It is often seen in spring-sown crops where itcan interfere with harvesting and seed cancontaminate grain.

ManagementSeedlings can be harrowed out, but onceestablished it is not readily controlled exceptwith hoeing. Vetches are generally susceptibleto sulfonylureas and some hormoneherbicides such as mecoprop-P and dicamba.


CORN SPURREY

Corn spurreySpergula arvensis


WW

60

Geographic locationCorn spurrey occurs in cereal fieldsor other cultivated land up to analtitude of 450m.

Soil typeIt occurs most frequently on lightsoils and surface-leached sandy soilswith a low pH.

Seed longevity: Longestever recorded over 170years


Seed weight: 1mg

Seeds/flower: 25

Seeds/plant: 1000-10 000



Lifecycle

Location

Competitive in

seed shed

flowering

germination

61CORN SPURREY

DescriptionIt is an annual weed, growing to 60cm tall,with white star-like flowers. The very narrowleaves are in groups of four.

Key featuresYoung plant: The cotyledons and first trueleaves are similar, both needle-shaped

Plant: The leaves are needle-shaped andarranged in whorls.

BiologyCorn spurrey can be a troublesome weed ofcereals, because of its dense mats of growth.Two generations can occur in one seasonbecause plants can set many seeds within 10weeks of germinating and just a fortnightafter flowering. There is a persistentseedbank. Seeds can be transported by birdsor mammals, or agricultural machinery.

ManagementRaising the pH over time will reduce cornspurrey and encourage the competitiveness ofthe crop.


CORNFLOWER

CornflowerCentaurea cyanus


WW

62

Geographic locationAlthough cornflower has becomerare as a wild plant, it may befound in waste places, roadsidesand rubbish tips, often as a gardenescapee. It is occasionally found inthe north-east of England andScotland.

Soil typeIt grows best in sandy loams andchalky clays.







Lifecycle

Location

Competitive in

seed shed

flowering

germination

63CORNFLOWER

DescriptionIt is an annual dicotyledon with upright habit,growing up to 1m tall. The stem and leavesare covered with woolly hairs and theflowerhead has a ring of usually bright blueflowers.

Key featuresPlant: The long thin leaves are covered withwoolly hairs.

Flowers: The flowers are bright blue.

BiologyCornflower can emerge in autumn- andspring-sown crops and can compete quite wellwith cereals; in the past it was capable ofreducing yields and interfering withharvesting. Autumn-germinating plantsoverwinter and produce more seeds thanspring-germinating plants.

ManagementUse a stale seedbed approach before sowingcrops. Harrows will control seedlings buthoeing is required for larger plants.Cornflower is susceptible to the main spring-applied herbicides.


COW PARSLEY

Cow parsleyAnthirscus sylvestris


WW

64

Geographic locationCow parsley grows throughoutBritain in hedgerows, verges,meadows and river banks.

Soil typeIt is found most frequently onalkaline soils. It does not like verywet or very dry conditions.



Seeds/floret: 2




Lifecycle

Location

Competitive in

seed shed

flowering

germination

65COW PARSLEY

DescriptionIt is a robust perennial dicotyledon,40 - 150cm tall, with upright branchedhollow stems. The leaves are divided two tothree times giving a feathery appearance.Small white flowers cluster in a denseumbrella-shaped head up to 6cm across.

Key featuresPlant: It has hollow furrowed unspottedstems, sometimes purplish in colour, andtriangular grooved leaf stems.

Flowers: Cow parsley is the first umbelliferto flower.

LookalikesCow parsley may be confused withshepherd’s-needle or other similar umbelliferswhen young: The leaflets are coarser and lessdivided than shepherd’s-needle, and thecotyledons longer and thinner than fool’sparsley.

BiologyCow parsley spreads into crop headlandsfrom hedgerows. It is usually found as aseedling in cereal crops. The seeds requirechilling to germinate and the seedlings growslowly. Mature plants can overwinter formingnew leaves in the spring; these die off as theflowering stem grows. The plant can alsoregenerate from the buds in the axils of thebasal leaves.

ManagementSpread may be reduced by ploughing andprobably moderate cultivation. It can bepartly controlled with cereal herbicides.


CREEPING BENT

Creeping bentAgrostis stolonifera


WW

66

Geographic locationCreeping bent grows throughoutthe British Isles up to an altitude of950m. It tolerates a wide range ofhabitats from salt marshes to sanddunes and grassland to arable.

Soil typeIt is found on all soil types, fromwet to dry, heavy or light soils.


Seeds/head: 100

Seeds/plant: 1000 - 10 000



Lifecycle

Location

Competitive in

seed shed

flowering

germination

67CREEPING BENT

DescriptionIt is a close-tufted, perennial grass 8 - 40cmtall, spreading by means of fine stolons whichproduce small roots when in contact withwater or moist soil. Leaves are long, narrowand pointed. The flowerhead forms an opendainty cylinder.

Key featuresPlant: Leaves are green or greyish-green andhairless; sheaths are rounded and smooth.

Flowers: The flowerheads are upright,cylindrical and usually open.

LookalikesCreeping bent may be confused with blackbent: creeping bent has a narrower, tighterflowerhead, and spreads by stolons notrhizomes, forming a loose tuft.

BiologyCreeping bent can be a weed of headlands,but seldom goes far into arable fields. Theplants can overwinter. In arable fieldspropagation by detached shoots is animportant means of spread.

ManagementSpring cropping can reduce the vigour.Reasonable control of creeping bent stolonscan be achieved with glyphosate, mosteffectively in uncropped land or summerfallows, but pre-harvest in early-harvestedcrops. Some residual herbicides may effectseedlings. Early cultivations can stimulateshed seed to germinate, so stale seedbeds maybe used to control the young germinatingplants, which can be killed by subsequentcultivation.


CREEPING THISTLE

Creeping thistleCirsium arvense


WW

68

Geographic locationCreeping thistle is found almosteverywhere in Britain, on cultivatedland or over grazed pastures.

Soil typeIt prefers loams rich in nitrogen andother nutrients, which are slightlydamp, and is an indicator of thincrops.




Seeds/head: 10 - 100




Lifecycle

Location

Competitive in

seed shed

flowering

germination

69CREEPING THISTLE

DescriptionIt is a perennial vigorous dicotyledon, withextensive creeping rhizomes. Plants grow up to150cm tall, often in extensive clumps.

Key featuresPlant: In the field plants group close together.The stems are unwinged and shiny and theflower stalks have many small flowerheads.

LookalikesCreeping thistle may be confused with spearthistle; the young plants of thistles are oftendifficult to tell apart. Creeping thistle is lesslikely to set fertile seed than other thistles.There are few marginal spines on creepingthistle. The large second leaf of spear thistle,is densely hairy.

BiologyCreeping thistle is one of the most troublesomeweeds of arable land. Dense patches caninterfere with cereal harvest and can be evenmore of a problem in potatoes and sugar beet.The plant dies back in winter while seeds arestill retained in the seed head. The separatesexes need to be within a few hundred metresfor seeds to be fertile, although some plants maybe self-fertile. Only about 3% of the seed isviable. Plants regenerate aggressively from theextensive system of branched, lateral roots, eachof which may give rise to new shoots, resultingin the formation of large clonal patches whichcan expand at the rate of 6m per year.

ManagementCreeping thistle is difficult to eradicate becauseof the extensive root system and because thewaxy coating on the leaves reduces herbicideadhesion. It can be controlled by combinationsof herbicides, ploughing and crop rotations, butavoid chisel ploughing or cultivations whichbreak up rhizomes as they readily regenerate. It is possible to drag the rhizomes to the surfacefor desiccation in fallows.


CRESTED DOG’S-TAIL

Crested dog’s-tailCynosurus cristatus


70

Geographic locationCrested dog’s-tail is generally aplant of lowland areas and itsdistribution is widespreadthroughout the British Isles. It isusually associated with pasture,meadow, or short swards but canbe found in fallow.

Soil typeIt likes neutral to alkaline-rich well-drained soils of low to mid fertility.

Seed weight: 0.5 mg

Seeds/head: 1

Seeds/plant: 1100



Lifecycle

Location

Competitive in

seed shed

flowering

germination

71CRESTED DOG’S-TAIL

DescriptionIt is a short, densely tufted perennial grass,wiry and upright. 5 - 75cm tall. The leafblades are narrow, fine and pointed.The flowerheads are densely packed withspikelets.

BiologyCrested dog’s-tail was formerly sown as apasture plant. It remains green all winter, butin the summer the leaves die off.

ManagementIt does not persist in regularly cultivated soilsand can be controlled with hoeing andharrowing.


CURLED DOCK

Curled dockRumex crispus


WW

72

Geographic locationCurled dock is found on verges,wasteland and arable land up to analtitude of 850m.

Soil typeIt likes nutrient-rich and compactedclay loams, and damp soils.



Seed weight: 2 mg

Seeds/head: 1

Seeds/plant: 3000 - 40 000



Lifecycle

Location

Competitive in

seed shed

flowering

germination

73CURLED DOCK

DescriptionCurled dock is a robust dicotyledon,50 - 120cm tall, though it may grow higher.It has long coarse basal leaves with wavyedges. The flowering shoot has individualflowers with heart-shaped petals in denseclusters.

Key featuresYoung plant: The cotyledons are moreslender than those of broad-leaved dock.

Plant: The leaves are 4 - 8 times longerthan broad, with wavy margins.

BiologyCurled dock is often abundant on arable landwith heavy, damp soils. It is found morefrequently in spring than winter crops andcan be difficult to control in crops other thancereals. Curled dock can overwinter as arosette of small leaves; it is the size of thisrosette which determines if the plant willflower the following year. Sometimes twocrops of seeds may be produced a season.Reproduction is mainly by seed but the plantmay produce vegetatively from rootfragments.

ManagementIn row crops, routine hoeing or pulling maybe required. Control established plants inuncropped land or in grass breaks withsuitable herbicides.


CUT-LEAVED CRANE’S-BILL

Cut-leaved crane’s-billGeranium dissectum


WW

74

Geographic locationCut-leaved crane’s-bill grows indisturbed warm soils up to analtitude of 350m.

Soil typeIt prefers loose, nutrient-rich, freshloam soils.




Seeds/flower: 5




Lifecycle

Location

Competitive in

seed shed

flowering

germination

75CUT-LEAVED CRANE’S-BILL

DescriptionIt is a hairy, semi-upright or sprawling,branched annual dicotyledon which grows to60cm tall. The small pink flowers have fivenotched petals.

Key featuresPlant: The deeply divided leaves have sevenlobes and a rounded outline. Stem and leafhairs frequently end in glands (a hand lensis required).

BiologyCut-leaved crane’s-bill is fairly common incereal crops, particularly on lighter soils andfallows. Reproduction is by seed and 80 - 90%of the seeds germinate. Autumn-germinatingplants can overwinter.

ManagementHerbicide control is variable with residualherbicides. Sulfonylureas have useful activity.


DAISY

DaisyBellis perennis


WW

76

Geographic locationDaisy is widespread throughout theBritish Isles, up to an altitude of915m, growing best in mown,grazed or trampled grassland, withlow or moderate amounts of bareground.

Soil typeIt prefers neutral or chalky soilswith pH>5.5, especially thosewhich are reasonably wet for aperiod.



Seeds/head: 150

Seeds/plant: 1000 - 10 000



Lifecycle

Location

Competitive in

seed shed

flowering

germination

77DAISY

DescriptionIt is a small perennial plant with a dense leafrosette and several upright leafless stems,approximately 5 - 15cm long, each bearing aflowerhead of typical daisy-like flowers.

Key featuresYoung plant: The leaves have bristly hairs.

LookalikesYoung daisy plants may be confused withCanadian fleabane: daisy is larger, slightlybluer and has more-rounded cotyledons.

BiologyDaisy is a potentially perennial, broad-leavedgrassland species that may be found incompacted moist soils in arable crops,particularly in field margins. A seriousproblem in turf grasses, it is seldom weedy inother crops and has some biodiversity value.Plants overwinter with green leaves showingand may even continue growing.Reproduction is mainly vegetative fromstolons, although the seeds can germinateover a wide temperature range. The flowersdevelop very fast in spring and summer.Seeds may be dispersed on feet and vehicles.

ManagementDaisy does not persist with routine cultivationor hoeing, and is susceptible to cereal andsome grassland herbicides.


DANDELION

DandelionTaraxacum agg.


WW

78

Geographic locationDandelion has many micro-speciesthat are difficult to tell apart.The whole group is foundthroughout the British Isles up toan altitude of 1220m, preferringfertile, disturbed and artificialhabitats.

Soil typeDandelions are found everywherebut in the water. They are mostfrequent where soils have pH>7.0.



Seed weight: 1 mg

Seeds/head: 180

Seeds/plant: 5000



Lifecycle

Location

Competitive in

seed shed

flowering

germination

79DANDELION

DescriptionDandelions are often variable and havesimilar micro-species. All have lobed leaves ina rosette on the ground with smooth flower-bearing stems. The flowers are large andyellow.

Key featuresPlant: Stems all have a milky sap.

BiologyDandelion can be found in low-growinggrassland, where there is limited disturbance.Plants can overwinter as a small rosette. New leaves are produced above those of theprevious season. Reproduction is by seed orby fragmentation of the long tap root. The plant is self-fertile, pollinated by insectsand the fruit is wind-dispersed.

ManagementAlthough found in arable crops, it is rarely anuisance as it does not tolerate cultivation ormany cereal herbicides.


DOVE’S-FOOT CRANE’S-BILL

Dove’s-foot crane’s-billGeranium molle


WW

80

Geographic locationDove’s-foot crane’s-bill occurs in awide range of habitats, up to analtitude of 550m. It prefers somebare ground and is not frequent inarable crops.

Soil typeIt is found on moderately dry, loosesandy soils, rich in humus andnutrients with pH>5.



Seeds/flower: 5




Lifecycle

Location

Competitive in

seed shed

flowering

germination

81DOVE’S-FOOT CRANE’S-BILL

DescriptionAn annual dicotyledon, 10 - 30cm tall.The leaves are cut to less than halfway andhave a rounded outline.

Key featuresPlant: It is distinguished from othergeraniums by the almost round leaves.The stems are covered by both long andshort hairs, so look softly hairy.

Flower: The pink petals have broad, bluntnotches at the tip.

BiologyDove’s-foot crane’s-bill is found on lightlygrassed margins and in arable crops,particularly in headland areas. Reproductionis by seed. It is most often seen in springcrops, but it can germinate in the autumn andoverwinter and grow vigorously in more openwinter crops.

ManagementIn more open winter crops, control can bevariable with residual herbicides.Sulfonylureas have some activity.


FAT HEN

Fat henChenopodium album


WW

82

Geographic locationThis is mainly a lowland weed,distributed widely in England andWales and the arable areas ofScotland. It prefers arable or othercultivated ground.

Soil typeCan be found in most soil types,but prefers moist, high-nitrogen,humus-rich loams and sandy soil.





Seeds/flower: 1

Seeds/plant: 3000 - 20 000



Lifecycle

Location

Competitive in

seed shed

flowering

germination

83FAT HEN

DescriptionIt is an annual dicotyledon, grey-green colour.It is upright, 20 - 50cm tall but growing to2m in crops. The leaves are diamond shaped.The flowers are green and inconspicuous inmany-flowered spikes.

Key featuresPlant: The plant is often narrow withoutspreading branches and the leaves aremealy.

LookalikesFat hen may be confused with commonorache: fat hen has broader cotyledons andthe undersides are often bright purple,unlike those of orache, which are brightgreen.

BiologyFat hen is one of the most important andwidespread of all weeds. Primarily it is aspring weed of broad-leaved crops such aspotatoes, sugar beet and open row crops.Seeds may germinate in autumn but onlyspring-germinating seedlings go on to flowerand set seed. Seeds are spread by cropcontamination and dispersed by birds andmammals; about 20% germinate immediately.Fat hen extracts large quantities of nutrientsfrom the soil. It has a highly persistentseedbank and seeds can remain dormant inthe soil for many years.

ManagementIt is vital to prevent seed shed from fat hen tocontrol population increase. There are anumber of broad-spectrum herbicides thatgive good control.


FIELD BEAN

Field beanVicia faba


84

Geographic locationField bean is found in lowlandareas in the midlands and south ofEngland and southern Scotland, asa volunteer in arable fields, as aresult of previous cropping.

Soil typeIt can grow on any soil type butprefers cultivated rich loams.

Seed weight: 550 mg



Lifecycle

Location

Competitive in

seed shed

flowering

germination

�

85FIELD BEAN

DescriptionIt is a robust annual dicotyledon, blue greenin colour, growing to 2m with two or morestems from the base. The leaves are dividedinto six large oval leaflets. Flowers are likethose of a pea with 5 or more growing inclusters in the leaf axils.

Key featuresYoung plant: It is very sturdy with novisible cotyledons.

BiologyField bean is found as a volunteer in arablefields as a result of previous cropping.It does not persist for long in the seedbank ifcontrolled in the crop. Field bean maygerminate in autumn and overwinter. It grows best in moist cool conditions.

ManagementDelaying cultivation allows predation of seedson the soil surface. Field bean is easilycontrolled by hormonal herbicides andsulfonylureas in cereals.


FIELD BINDWEED

Field bindweedConvolvulus arvensis


86

Geographic locationField bindweed is found in a widevariety of lowland habitatsincluding verges, waste tips, anddisturbed and arable ground.

Soil typeIt likes dry, warm, nutrient-richdeep and loose loams.



Seed weight: 10 mg

Seeds/flower: 1 - 4

Seeds/plant: 550



Lifecycle

Location

Competitive in

seed shed

flowering

germination

87FIELD BINDWEED

DescriptionIt is a perennial dicotyledon, 20 - 100cm tall,which trails or climbs up other plants.The flowers are trumpet-shaped, usuallystriped pink and white.

Key featuresPlant: The heart-shaped leaves are roundedat the tip and the plant twines to the left,anti-clockwise.

LookalikesField bindweed may be confused withblack-bindweed as young plants.The difference is in the cotyledons; black-bindweed has long cotyledons with shortstalks, while field bindweed has ovalcotyledons, notched at the tip.

BiologyField bindweed is a persistent andtroublesome perennial weed. It can be foundboth on disturbed arable land and onundisturbed sites such as field margins.Field bindweed plants die back in autumn.The roots overwinter although they can besusceptible to freezing. The plants canregenerate from fragments of horizontal rootsand, though seed set is unlikely in Britain, thelong-lived seeds rapidly germinate. Seeds maybe dispersed by birds. It can severely reducecrop yield and also cause difficulties withharvesting. Field bindweed does not persist inlong grass leys or in grazed or mown land.

ManagementThe leaves and stems are difficult to wet withherbicides, but spring herbicides for broad-leaved weeds in cereals are effective. It can becontrolled in fallow with glyphosate.


FIELD FORGET-ME-NOT

Field forget-me-notMyosotis arvensis


WW

88

Geographic locationForget-me-not is usually found onarable land or other habitats withbare soils. It can grow above analtitude of 600m.

Soil typeThere is no particular soil typeassociated with this weed.




Seeds/flower: 4




Lifecycle

Location

Competitive in

seed shed

flowering

germination

89FIELD FORGET-ME-NOT

DescriptionIt is a short, softly hairy annual or biennial,10 - 50cm tall with the lower leaves forming arosette. The flower stalk curves at the end intoa scroll with the buds to one side. The smallflowers have five blue petals and a yellow tube.

LookalikesYoung field forget-me-not plants may beconfused with daisy, but daisy has nohairs on the cotyledons.

BiologyField forget-me-not is common in wintercereals and winter oilseed rape and can alsooccur in spring crops. It is generally not verycompetitive but can occur in very highnumbers competing with the young crop.The mature plant can overwinter as a smallrosette and seedlings which germinate inautumn can also survive winter. The plantreproduces by seed. Seeds can be moved byingestion by animals. Plants may re-sproutand flower when the leaves have beenremoved.

ManagementIt is controlled by a range of residualherbicides and some foliar treatments, but nothormonal herbicides.


FIELD HORSETAIL

Field horsetailEquisetum arvense


90

Geographic locationFiled horsetail is widespread aroundBritain in many habitats includingroadsides, paths, gardens and wasteground up to an altitude of 1000m.

Soil typeIt can tolerate a wide range of soilmoisture and types.



Lifecycle

Location

Competitive in

seed shed

flowering

germination

91FIELD HORSETAIL

DescriptionHorsetails belong to an ancient family of theirown and have no closely related existingrelatives. The leaves have reduced to scalesand the stem is the main photosyntheticorgan. Stems contain a large amount of silica.A coarse-looking perennial, it tends to occurin patches. It grows up to 80cm tall and stemsare wiry with whorls of needle-like branches.The fertile stem ends in an organ thatproduces spores (sporangium).

Key featuresPlant: The plants have wiry stems whichfeel gritty when rubbed due to the highsilica content. Leaves are like bristles. The rhizomes are black.

BiologyHorsetail can be a problem in perennialcrops, where it is not readily controlled.The wiry stems interfere with harvestingarable crops. It reproduces mainly fromrhizome fragments and also from the short-lived spores. Plants overwinter as rhizomes,producing fertile shoots in April and sterileshoots later.

ManagementIt is difficult to control with herbicides,but does not readily persist with routinecultivation.


FIELD PANSY

Field pansyViola arvensis


WW

92

Geographic locationField pansy is a weed of cultivatedland, or other open lowlandhabitats.

Soil typeIt is found on all soil types with anopen aspect but less frequently onpoorly aerated or waterlogged soils.




Seed weight: 0.4 mg


Seeds/plant: 2500



Lifecycle

Location

Competitive in

seed shed

flowering

germination

unknown

93FIELD PANSY

DescriptionA rather week semi-upright annualdicotyledon, up to 30cm tall. The pale-greenlobed or toothed leaves have deeply dividedprojections at the base. The typical pansyflowers are cream, possibly tinged withpurple, and with a violet projection or spurbehind.

Key featuresPlant: Field pansy has a less robustappearance than wild pansy.

Flowers: It is distinguished from wild pansyby its paler smaller flowers. The petals areshorter than the sepals.

BiologyField pansy is very widespread in cereal crops.It may be more common in winter crops buthas increased in spring crops, possiblyencouraged by winter cropping. Autumn-germinating field pansy can overwinter andthese plants will flower early the followingyear. The seed is dispersed from an explosiveseed head. The plant stems can interfere withcombine cutter bar operation.

ManagementResidual herbicide treatments are generallyeffective in autumn- and spring-sown crops.


FOOL’S PARSLEY

Fool’s parsleyAethusa cynapium


94

Geographic locationDistributed towards the south ofBritain, fool’s parsley is found oncultivated lands, in undergrowthand water meadows.

Soil typeIt is usually found on nutrient-richsoils, which may be chalky orneutral to alkaline loams.


Seed weight: 2.5 mg

Seeds/floret: 2

Seeds/plant: 500



Lifecycle

Location

Competitive in

seed shed

flowering

germination

unknown

95FOOL’S PARSLEY

DescriptionIt is an annual, very variable in height, up to50cm tall but usually only about 20cm onarable land. The leaves are repeatedly divided,similar to those of parsley. The small whiteflowers are in flat-topped flowerheads.

Key featuresFlowers: Fool’s parsley has downward-pointing projections (bracteoles) under eachflower.

LookalikesFool’s parsley can be mistaken for wildcarrot at the seedling stage. The cotyledonsof fool’s parsley are wider and shorter andthe first true leaves less finely divided thanthose of wild carrot.

BiologyThe plants germinate in spring and die backafter flowering.

ManagementFool’s parsley can be controlled in arable landby grass breaks of 2-3 years and reduced bygrowing shading break crops. Seedlings canbe successfully harrowed when small. It is notcontrolled by hormone herbicides. Treat whenyoung with sulfonylureas or contactherbicides in cereals.


GARLIC MUSTARD

Garlic mustardAlliaria petiolata


96

Geographic locationGenerally a lowland plant, garlicmustard inhabits a wide range ofhabitats, including hedgerows,waste ground, farmyards andgardens.

Soil typeIt prefers fertile moist soils but cangrow on all but the most acidic.


Seed weight: 2.5 mg

Seeds/flower: 20



Lifecycle

Location

Competitive in

seed shed

flowering

germination

97GARLIC MUSTARD

DescriptionIt is a biennial or perennial dicotyledon,20 - 120cm tall. The stem is upright andmuch branched with heart-shaped totriangular, shiny and strongly veined leaves.Up to 30 small white flowers with four petalsform at the top of the flower stalk.

Key featuresPlant: The leaves smell of garlic whencrushed.

BiologyGarlic mustard grows in field margins andhedgerows and does not tolerate cultivation orcrop competition in arable fields. It overwintersas a rosette of small leaves. The seeds mayremain dormant for 18 months or longer.

ManagementCare should be taken to reduce seed returningto the seedbank.


GREAT BROME

Great bromeAnisantha diandra


98

Geographic locationGreat brome grows generally in thesouth and east of England, but hasspread as far north as southernScotland. It is found in arablefields, waste ground and roadsides.

Soil typeIt prefers sandy soils and dunes.


Seed weight: 10 mg



Lifecycle

Location

Competitive in

seed shed

flowering

germination

unknown

99GREAT BROME

DescriptionIt is an annual grass, 35 - 90cm tall. It isloosely tufted or solitary, usually spreadinghabit. Leaves are hairy towards the top ofthe plant. Flowerheads are very open withsingle spikelets on each branch.

Key featuresGreat brome looks like a larger form ofbarren brome.

BiologyGreat brome emerges in the autumn and has arelatively short lived seed.

ManagementMoving to spring cropping reduces theinfestation. Mouldboard ploughing to 15cmimmediately after harvest assists control.


GREEN FIELD-SPEEDWELL

Green field-speedwellVeronica agrestis


WW

100

Geographic locationGreen field-speedwell preferscultivated land, gardens orallotments, usually below analtitude of 400m.

Soil typeIt prefers well-drained acidic soils,but may be present on chalky soilswhere there is surface leaching.


Seed weight: 0.6 mg


Seeds/plant: 1000 - 10 000



Lifecycle

Location

Competitive in

seed shed

flowering

germination

101GREEN FIELD-SPEEDWELL

DescriptionIt is a creeping hairy annual, 10 - 30cm tall,forming a loose cushion. It has oval palegreen leaves with blunt rounded teeth. Thesmall very pale blue flowers are borne on longstalks growing from the leaf axils.

Key featuresFruit: The two-lobed fruit is longer than it iswide, and is covered in many glandular hairs.

BiologyGreen field-speedwell is found in springcereals and vegetable crops but is not a verycompetitive weed in vigorous cereal crops. It germinates mainly in spring although someseeds may germinate in autumn. It needsrelatively high temperatures for germinationso it germinates later than other species.

ManagementIn row crops it can be controlled byharrowing or hoeing if herbicides are notavailable. It does not persist in grass leys.Wide range of herbicide options, althoughneed to consider resistance implications.


GROUNDSEL

GroundselSenecio vulgaris


WW

102

Geographic locationGroundsel grows up to an altitudeof 500m, in open habitats such asarable soils, waste places andrubbish tips.

Soil typeIt grows best in loose sandy loams,or nutrient-rich sandy soils with apH usually >6.




Seeds/head: 40




Lifecycle

Location

Competitive in

seed shed

flowering

germination

103GROUNDSEL

DescriptionIt is a short hairy annual, 10 - 40cm tall.The stem is upright with loose cut leaves.The flowerhead, which contains a number ofdaisy-like flowers, may curve over.

Key featuresFlower: The sepal-like bracts outside theflowerheads have black tips.

BiologyGroundsel is common in arable fields. With ashort lifespan it is able to produce severalgenerations in one year. Although increasinglyfound in autumn and spring arable cropsbecause of its abundance in fallows, it isseldom a major problem. Groundsel mayincrease in stubble-sown crops, as itsuccessfully colonises firm seedbeds.

Seeds germinate throughout the whole yearand in a good year plants shed seeds by earlyJune which can give rise to more than onegeneration a year. Plants are able tooverwinter. The seeds can be dispersed bywind, but the wetted fruits become sticky andcan be carried by animals or humans.

ManagementGroundsel is controlled by some residualherbicides but can reappear in open crops inspring, where it is susceptible to a wide rangeof foliar herbicides. It is a nuisance inperennial crops where herbicides choices are limited.


HEDGE MUSTARD

Hedge mustardSisymbrium officinale


WW

104

Geographic locationHedge mustard occurs in cultivatedground, hedgerows and wasteground, including field margins, inlowland areas up to analtitude of 350m.

Soil typeIt likes dry, loose, nutrient-richloams and sandy and stony soils.



Seeds/head: 9 - 18

Seeds/plant: 2700



Lifecycle

Location

Competitive in

seed shed

flowering

germination

105HEDGE MUSTARD

DescriptionIt is an annual or over-wintering annual,30 - 60cm tall, with almost horizontalbranching stems and deeply cut spear-shapedand lobed leaves. The yellow flowers are verysmall with four petals, in flat-toppedflowerheads.

Key featuresPlant: It is a much-branched mustard-typeplant. The branches are usually parallel tothe ground.

BiologyHedge mustard appears in spring-sown cropsand poorly competitive winter cereals.The flowers are pollinated by insects. Hedgemustard reproduces only by seed, which iswind-dispersed.

ManagementA stale seed-bed approach may be used tocontrol this species.


HEMLOCK

HemlockConium maculatum


106

Geographic locationHemlock is generally a lowlandplant and usually prefers dampersoils on waste tips and roadsides,and in perennial crops.

Soil typeIt prefers damper, nutrient-richsoils.


Lifecycle



Location

Competitive in

seed shed

flowering

germination

107HEMLOCK

DescriptionIt is a biennial dicotyledon, 50 - 200cm tall,ferny leaves with angular leaflets and whitelacy flowerheads.

Key featuresPlant: It has purple-spotted, hairless stemsand an unpleasant mouse-like smell. It isextremely poisonous.

BiologyHemlock is most often a weed of perennialcrops, as it does not persist in regularlycultivated fields. It germinates in autumn andoverwinters as a rosette of divided leaves.The plants can live for one or two years.

ManagementControl the plant in arable crops toprevent persistence into grass leys.The weed is very toxic to livestock. Plantsshould be controlled with glyphosate and alllivestock should be excluded until the weedhas died back completely.


HENBIT DEAD-NETTLE

Henbit dead-nettleLamium amplexicaule


WW

108

Geographic locationHenbit dead-nettle is common onarable and fallow land to the southeast of Britain. It grows up to analtitude of 450m.

Soil typeIt prefers light dry humus andsandy loam soils which are nutrientrich.


Seed weight: 0.5 mg

Seeds/plant: 200

Lifecycle



Location

Competitive in

seed shed

flowering

germination

unknown

109HENBIT DEAD-NETTLE

DescriptionIt is an annual bushy and brancheddicotyledon, 25cm tall. The pink flowers areless conspicuous than those of other dead-nettles.

Key featuresYoung plant: The first true leaves arerounded.

Plant: The leaves are rounded with wavyedges and the upper leaves appear to circlethe stem.

LookalikesHenbit dead-nettle may be confused withred dead-nettle; the dead-nettles can bedifficult to distinguish at the seedling andyoung plant stages. The first true leaves ofhenbit dead-nettle are paler than the otherdead-nettles.

BiologyHenbit dead-nettle is common on arable land,where it is most often found in winter crops.Plants are self-fertile and in dull weather canfertilise themselves while in the bud.The seeds germinate in spring and summerand small plants can overwinter.

ManagementIt may be controlled by spring cropping andby a range of herbicides suitable for broad-leaved weeds.


ITALIAN RYE-GRASS

Italian rye-grassLolium multiflorum


110

Geographic locationItalian rye-grass is mainly found inthe south of Britain, on verges andfield borders, mainly in lowlandareas at altitudes below 400m.

Soil typeIt prefers well-drained soils of amoderate pH and high nitrogen.


Seed weight: 2.5 mg

Seeds/head: 100

Lifecycle



Location

Competitive in

seed shed

flowering

germination

111ITALIAN RYE-GRASS

DescriptionIt is a leafy annual or biennial grass,30 - 100cm tall. The stems are tufted orsolitary with an upright or spreading habitand green hairless leaves. Italian rye-grasstends to be larger, stouter and more denselytufted than perennial rye-grass.

Key featuresPlant: It is distinguished from perennialrye-grass by the leaves which are rolled inthe shoot, and the large auricles.

Flowers: The lower bract is awned.Flowerheads are arranged at 90degrees tothe flower stem.

BiologyItalian rye-grass is an economically importantforage grass increasing as a weed problem inmany areas of the UK. It can grow from seedor vegetatively from badly ploughed-in tufts,or rooting stems. Autumn-germinating plantscan overwinter. It can become a severe weedin arable crops where pasture forms part ofthe rotation.

ManagementUse glyphosate in fallows, as a pre-harvesttreatment and in break crops. Reducing seedspread by cleaning equipment between fieldsand avoiding using fields with heavy rye-grasspopulations will greatly decrease rye-grassproblems.


IVY-LEAVED SPEEDWELL

Ivy-leaved speedwellVeronica hederifolia


WW

112

Geographic locationIvy-leaved speedwell is a lowlandplant, growing up to an altitude of380m. It prefers open arable land,gardens and other bare or disturbedsoils. It grows particularly in wintercereals, but is increasingly found inspring cereals in the west andnorth, as populations have beenencouraged by winter cropping.

Soil typeIt is found on warm, loose,nutrient-rich mild loam soils.




Seeds/flower: 2


Lifecycle



Location

Competitive in

seed shed

flowering

germination

113IVY-LEAVED SPEEDWELL

DescriptionA creeping hairy branched annual with ivy-shaped five-pointed leaves. The flowers aresmall, lilac to white in colour and the fruit isthree-dimensional, heart shaped and hairy.

Key featuresYoung plant: The cotyledons end in a knob.Fruit: The fruit has no lobes and is hairy.

BiologyIvy-leaved speedwell reproduces by seed,which germinates in cold conditions in lateautumn or early spring.

ManagementAutumn residual herbicides such aspendimethalin, diflufenican and others areeffective but late-germinating seedlings canescape. Spring foliar treatments based onsulfonylureas plus contact herbicides areeffective in cereals.


KNAPWEED

KnapweedCentaurea nigra


WW

114

Geographic locationKnapweed grows at altitudes of upto 600m in waste ground, fieldmargins and roadsides, meadowsand pastures.

Soil typeIt can tolerate a wide range of soils,but prefers unmanured sites.


Seed weight: 2.5 mg

Seeds/flower: 1

Seeds/plant: Up to 1000

Lifecycle



Location

Competitive in

seed shed

flowering

germination

115KNAPWEED

DescriptionIt is a downy, perennial dicotyledon, withupright, tough, usually branched stems,30 - 60cm tall. It has a rosette of leaves at thebase and purple thistle-like flowerheads.

Key featuresYoung plant: The first true leaves have adark colour.

BiologyKnapweed is more common in olderpastures and is usually found on themargins of arable land. Although theplant dies back overwinter it is aperennial. Plants mainly reproduce by seed,which may survive for several years, if theysurvive predation by insects or smallmammals. Plants may reproduce vegetativelyif side shoots become detached from theparent plant.

ManagementIt does not persist in cultivated soils and isreadily controlled with glyphosatein uncropped breaks.


KNOT-GRASS

Knot-grassPolygonum aviculare


WW

116

Geographic locationKnot-grass is found up to analtitude of 550m in all areas ofBritain. It is common on arable andother disturbed or trampled land,demolition sites, soil heaps, manureand waste heaps, paths and tracksbut not woodland or very wethabitats.

Soil typeIt is most frequently found on barefertile soils, but not waterloggedsites.



Seeds/flower: 1


Lifecycle



Location

Competitive in

seed shed

flowering

germination

117KNOT-GRASS

DescriptionIt is a low-growing spreading annual,10 - 100cm long, with many branched stems; the plants may be creeping or upright and in acereal crop may have vertical shoots. Theleaves are narrow and spear-shaped.

Key featuresYoung plant: The hypocotyl is long andcrimson.

Plant: The stems do not end in a flowerhead,as the tiny pink flowers occur in the leaf axils.

BiologyKnot-grass tends to be a worse weed in openand spring sown crops, i.e. spring beans, sugarbeet, kale, linseed and potatoes, than in wintercereals, beans and even wheat crops.It reproduces from seeds, which can form apersistent seedbank. The seeds are relativelylarge; they may be dispersed in mud on footwearand on tyre treads and can survive ingestion bystock and by birds. They germinate largely inspring and are returned to a state of secondarydormancy when late spring temperatures rise, soproduce only one generation a year. Autumn-germinating seeds do not survive the winter. Thevegetative part of the plant can regenerate if cutoff during the growing season.

ManagementDormancy is broken by winter chilling so springcultivation can increase plant numbers. Shallowburial promotes emergence compared with deepploughing but ploughing will increase thepersistence of seedbanks. In cereals, combinationsof hormone, sulfonylurea and contact herbicidesare often needed for good control. Control canbe variable in spring brassica crops, beet,potatoes and legumes if soil conditions are dryand residual herbicides do not work well.


seed shed

flowering

germination

LINSEED

LinseedLinum usitatissimum


118

Geographic locationLinseed is found in southern Britainas a volunteer from previous crops,or the result of scattered bird seedon banks and verges.

Soil typeIt can grow on a wide range of soiltypes.

Seed weight: 8 mg

Seeds/plant: <1 year



Lifecycle

Location

Competitive in

seed shed

flowering

germination

�


119LINSEED

DescriptionIt is a hairless, annual dicotyledon, up to75cm tall. The plants have slender stems andspear-shaped leaves. The large, usually blue,flowers have 5 petals.

Key featuresYoung plant: The three-veined leaves arewell spaced and needle-shaped.

Flowers: All the sepals are pointed and thepetals fall off early in the afternoon.

BiologyLinseed and flax are different cultivars ofLinum usitatissimum. The tall form, flax, israrely grown for linen fibre. The short formlinseed is the usual crop grown to producelinseed oil. Both can occur as crop volunteers,generally in the season following the crop.Autumn-germinating plants may be killed bywinter frosts.

ManagementControl can be helped by a stale seedbed afterthe crop is harvested to encourage predationand germination of seeds. Linseed issurprisingly tolerant of a wide range ofherbicides but may be controlled with somehormone herbicides.

LONG-HEADED POPPY

Long-headed poppyPapaver dubium


WW

120

Geographic locationLong-headed poppy is a lowlandplant found in arable fields,wastelands and gardens. It is nowlargely restricted to the chalk ofsouthern England, though it doesoccur on outlying sites in Norfolk,Northamptonshire and Cornwall.

Soil typeIt is found on light or heavy chalkysoils.


Seed weight: 0.1 mg

Seeds/flower: 2000

Seeds/plant: 18 000

Lifecycle



Location

Competitive in

seed shed

flowering

germination

121LONG-HEADED POPPY

DescriptionIt is an upright, annual 30 - 60cm tall. Thestems are hairy at the base with the hairsparallel to the stem. The leaves at the baseform a rosette of divided segments. Thebroken stem bleeds a white sap. The largeflowers have four red petals without blotches.The seedhead is long.

Key featuresFruit: The seedhead is long and smooth.

BiologyLong-headed poppy occurs as a cerealweed, though it is less frequent on arable landthan common poppy. The plants reproduceentirely by seed; autumn-germinating plantscan overwinter. The small green seed headscan block combine sieves at harvest and theseeds can contaminate oilseed rape seedsamples.

ManagementIt is readily controlled in cereal crops anduncropped land with herbicides.

Herbicide resistance has not been reported inthe UK.


LOOSE SILKY BENT

Loose silky bentApera spica-venti


WW

122

Geographic locationLoose silky bent is not widelydistributed but found in arablefields, sandy tracks and roadsidesup to an altitude of 650m.

Soil typeIt grows in bare ground on lightsoils such as sand and light loam.




Lifecycle



Location

Competitive in

seed shed

flowering

germination

123LOOSE SILKY BENT

DescriptionIt is a tufted or solitary annual grass growing to100cm tall, with stout or slender, green or purplestems. It has a fine appearance with smooth leafsheaths. The flowerhead is oblong, open andfeathery.

Key featuresPlant: The plant does not spread by rhizomes orstolons.

Flowers: The flowerhead has more-openspreading branches than other bents.

LookalikesLoose silky bent may be confused with black-grass at the young plant stage of developmentbecause of the reddish/purple colouring of theleaf sheath. When mature, loose silky bent hasmore-limited tillering than black-grass, does notproduce rhizomes or stolons unlike other bents,and tends to be more upright in later habit.

BiologyLoose silky bent is occasionally very abundant incereal fields. It seeds profusely with light seedswhich can travel long distances. Seeds usuallygerminate in autumn and overwinter as youngplants. Because seeds have a relatively longsurvival, germination can be delayed until theconditions are favourable. The seeds can shed andgerminate before a crop matures, making controldifficult.

ManagementGrass breaks or spring cropping can reducepopulations. In reduced tillage situations allowseedlings to germinate and then cultivate, orharrow seedlings when the soil is dry.

Wide range of herbicide options. Some resistanceto ureas and amides and ALS inhibitors has beenfound in mainland Europe.


MEADOW BROME

Meadow bromeBromus commutatus


124

Geographic locationMeadow brome is a lowland plantof southern England, growingespecially on cultivated land and inrough grassland, damp meadows,verges and track edges.

Soil typeIt is most frequently found onmoist, relatively heavy soils.

Seed weight: 5 mg

Lifecycle



Location

Competitive in

seed shed

flowering

germination

�

125MEADOW BROME

DescriptionIt is an annual or biennial grass, 40 - 120cmtall. It is loosely tufted or solitary, withslender to moderately stout. stems, roughfinely pointed leaf blades and tubular splittingsheaths. The flowerhead is loose.

Key featuresPlant: The stems are hairy.Flowers: The ripe flowerheads droop to oneside.

BiologyMeadow brome most commonly infestsheadlands of winter cereal crops and is rarelyseen in spring-sown crops. It completes itslife cycle within one year and does notreproduce from vegetative fragments.

ManagementShed seed should be kept on the surface for4 weeks before cultivation to allow ripening.Plants should be killed with a glyphosateapplication before sowing subsequent crops.Deep cultivations or mouldboard ploughing,to bury seeds below 20cm, will reducenumbers in following years. Spring croppingis effective for control, as is fallow land, aslong as emerging plants are controlled beforesetting seed. Mow, or spray with glyphosate,before flowering.

Moderate control can be achieved by a varietyof herbicides in cereals. Greater control maybe achieved in broad-leaved crops.


NIPPLEWORT

NipplewortLapsana communis


126

Geographic locationNipplewort is a lowland speciesfound on arable land and otherbare disturbed ground up to analtitude of about 300m.

Soil typeIt occurs in loams and clays that arenutrient-rich with moderatenitrogen and often damp.


Seed weight: 2 mg

Seeds/head: 30


Lifecycle



Location

Competitive in

seed shed

flowering

germination

127NIPPLEWORT

DescriptionIt is a hairy, upright, branched, leafy annualor biennial dicotyledon, 30 - 120cm tall.Basal leaves are oval and toothed but theupper stem leaves are spear-shaped. Flowersare yellow, small and look similar to those ofdandelion.

Key featuresPlant: The plant has stiff hairs at the baseand is smooth above; it is much branchedand angular, and fairly loosely rooted.

Flowers: The open spikes of yellowdandelion-like flowers are smaller thanthose of other yellow composites.

BiologyNipplewort is common on cultivated land,particularly in cereals, though its populationis probably decreasing. Nipplewort is morecommon in winter cereals, but is also foundin spring crops in colder, wetter areas. It hasrelatively large seeds which may contaminatecrop seeds.

Autumn-germinating seeds can overwinter asrosettes and become very tall plants. Its formvaries widely, depending on location.

ManagementNipplewort is controlled by a range ofherbicides suitable for broad-leaved weeds.


OAT

OatAvena sativa

Value to BiodiversityResistanceSpring CropsWOSR�WW

128

Geographic locationCultivated oat is found in lowlandareas around Britain as a volunteerfrom previous arable crops.

Soil typeIt occurs on conventional arablesoils; it is slightly more tolerant oflow pH than other grain crops.


Seed weight: 66 mg

Lifecycle



Location

Competitive in

seed shed

flowering

germination

129OAT

DescriptionIt is an annual grass with stems up to 100cmtall. It is generally a soft green colour beforeripening. Leaf blades are broad and hairless.The flowering spike is open, with groups oftwo or three flowers in each spikelet, thelower of which may be awned.

Key featuresFruit: The lemmas are broad with just thetip notched. The grains do not have a tuftof hair at the base.

LookalikesCultivated oat and wild-oat are difficult totell apart as plants. The ligule of cultivatedoat is shorter and blunter than that of wild-oat. The leaves are hairless. When mature,cultivated oat is generally broader-leaved,paler and more robust than wild-oatspecies.

BiologyMost cereal oats are not very winter-hardy,although volunteers of winter varieties surviveafter autumn germination in subsequentcrops. They do not persist as weeds for morethan a couple of years, because the seedbankis less persistent than for wild-oat, and theyare not as competitive as wild-oat.

ManagementUse stale seedbed strategies to allow shed seedto germinate. Grass leys of 2-3 years reduceseed populations. Otherwise treat as wild-oat.

Herbicides suitable for wild-oat are effectiveon cultivated oats.


OILSEED RAPE

Oilseed rapeBrassica napus ssp. oleifera

Value to BiodiversityResistanceSpring CropsWOSR� �WW

130

Geographic locationOilseed rape is mainly a lowlandplant but has been found ataltitudes of up to 420m inCumbria. It occurs frequently alongroadsides, often as a result offalling from lorries.

Soil typeOilseed rape prefers disturbed soils.


Seed weight: 5 mg

Seeds/plant: 8000 - 10 000

Lifecycle



Location

Competitive in

seed shed

flowering

germination

131OILSEED RAPE

DescriptionIt is an annual or biennial hairlessdicotyledon, with a waxy coating giving theindented leaves and stem a blue-grey colour.Leaves clasp the flowering stem. Flowers areusually bright yellow.

Key featuresPlant: Leaves are smooth-surfaced and blue-green in colour.

BiologyOilseed rape volunteers commonly occur insubsequent crops and can reduce wheat yieldssignificantly. Volunteers of spring rape varietiescan be a serious problem in the winter rapecrop. Autumn-germinating plants stand wellover winter. Growth mainly occurs betweenmid March and late August. The plant onlyreproduces by seed.

ManagementAfter harvest, oilseed rape seeds should be lefton the soil surface for as long as possible, atleast 2 to 3 weeks. A high percentage of seedwill germinate in the autumn and can then becontrolled by cultivations or by herbicides.Soil-incorporated seeds develop inducedsecondary dormancy and can persist forseveral years.


ONION COUCH

Onion CouchArrhenatherum elatius


132

Geographic locationThe bulbous form of false oat-grass,onion couch is a common arableweed found all over the British Islesexcept for high ground above analtitude of 550m. It is found in awide variety of habitats on roadsideverges, river banks and other wasteground, and in some arable fields.

Soil typeIt tolerates a wide range of soil pH,from very limey soils and evenlimestone scree to neutral soils.



Seeds/head: 100

Lifecycle



Location

Competitive in

seed shed

flowering

germination

133ONION COUCH

DescriptionOnion couch is a very tall, loosely tuftedperennial grass, growing to 150cm. A seriesof bulbous swellings at the base of stem givesthe grass its common name of onion couch.Leaf blades are flat and finely pointed. The flowerhead is compact and narrow.

Key featuresPlant: Bulbous swellings at the base of thestem and yellowish roots.

Flowers/fruit: The spikelets have a singlelong awn.

BiologyOnion couch is a troublesome weed anddifficult to control on cultivated fields. The plants can overwinter and new shoots areproduced from March. The non-bulbous formcan grow from stem bases detached duringploughing, but the bulbous form grows onlyfrom seed. It is encouraged by direct drillingof arable crops.

ManagementMouldboard ploughing can bury the stembases too deep to emerge. Best control will beachieved by herbicides such as glyphosateapplied when the grass is actively growing.This can be difficult near and around cropspost-emergence and is best done in uncroppedland such as summer fallows.


PALE PERSICARIA

Pale persicariaPersicaria lapathifolia


WW

134

Geographic locationPale persicara is associated with awide range of habitats in both openand disturbed sites and in cultivatedfields, up to a maximum recordedaltitude of 450m. It is less frequentin the north on less organic soils.

Soil typeIt prefers slightly acid soils rich inhumus and nutrients, often sandyloams.



Seed weight: 3 mg


Lifecycle



Location

Competitive in

seed shed

flowering

germination

135PALE PERSICARIA

DescriptionIt is an annual of medium height 30 - 80cmtall, with slightly hairy, often red stems.Leaves are strap-shaped and may be blotchedwith black. The flower spike is stout, packedwith tiny flowers.

Key featuresYoung plant: The first true leaves are silverywith short hairs.

Plant: The sheath covering the leaf stembase has no hairs and lies loosely againstthe stem. The flowering stem is hairy.

LookalikesPale persicaria may be confused withredshank: the first true leaves of palepersicaria are long and narrow and havesilvery hairs, which also cover the stem; thefirst true leaves of redshank are broad andthe plant is not hairy.

BiologyPale persicaria is a common weed in all crops,particularly spring-sown ones. It may occurin open crops of winter wheat, possiblypreferring more organic soils than the similarredshank. Flowers are self-pollinated or cross-pollinated by insects. The seeds maygerminate in spring only after chilling.

ManagementIt is controlled by a wide range of hormoneand sulfonylurea herbicides in cereals and bymany residual herbicides in most spring-sownbroad-leaved crops.


PARSLEY-PIERT

Parsley-piertAphanes arvensis


136

Geographic locationParsley-piert is found on arableland and droughted soils, and onother sites with a large exposure ofbare soil, usually in lowlandhabitats up to an altitude of 300m.

Soil typeIt grows in dry alkaline or acidicsoils, but rarely below pH 5.



Seeds/flower: 1

Lifecycle



Location

Competitive in

seed shed

flowering

germination

137PARSLEY-PIERT

DescriptionIt is a small creeping annual dicotyledon, upto 10cm in size. The leaves have three lobes,each divided further into five to seven parts.

Key featuresPlant: The plant appears to have noflowers, as they are green andinconspicuous.

BiologyParsley-piert grows before the crop fullyestablishes and in late summer after harvest.It mainly germinates in autumn from seedswhich come from a persistent seedbank.Young plants can overwinter. It is verydrought resistant.

ManagementIt can be reduced by ploughing and springcropping. Grass breaks can reduce theseedbank. It is encouraged by fallow, reducedcultivation and direct drilling, so mouldboardploughs should be used.


PEA

PeaPisum sativum


138

Geographic locationField pea occurs in arable areas inBritain as a volunteer from previouscrops and may also occur on wasteground and field margins.

Soil typeIt prefers well drained, highly fertilesoils.

Seed weight: 275 mg

Lifecycle



Location

Competitive in

seed shed

flowering

germination

139PEA

DescriptionIt is a scrambling dicotyledon up to 1m high,heavily branched, with leaves ending intendrils or reduced to just tendrils. Peaflowers are large and may be pink or white.

Key featuresYoung plant: Stiff but small with no visiblecotyledons. There is a pair of projections atthe base of each leaf.

BiologyThere are a large number of cultivated strainsof pea, grown for food and animal fodder.Although plants can germinate in autumn andoccasionally withstand heavy frost, theyusually germinate in spring. They prefer coolmoist growing conditions and are shallow-rooted and therefore susceptible to drought.Seeds can germinate at temperatures above4.5°C. Although peas emerge and can causelodging in cereal fields, they do not persist toa second season if controlled.

ManagementSeedlings emerging in autumn or early springare usually killed by continuous frost. A widerange of herbicides are available to controlpeas in cereals and grass crops.


PERENNIAL RYE-GRASS

Perennial rye-grassLolium perenne

Value to BiodiversityResistanceSpring CropsWOSR�WW

140

Geographic locationPerennial rye-grass is found on awide range of habitats, which mayhave been sown for grass, inmeadows, pastures and ondemolition sites. It does not growabove an altitude of 400m.

Soil typeIt occurs on soils within the pHrange 5 - 8.


Seed weight: 2 mg

Seed/head or capsule: 100

Lifecycle



Location

Competitive in

seed shed

flowering

germination

141PERENNIAL RYE-GRASS

DescriptionIt is a large, dark-green, glossy, tuftedperennial grass, 30 - 60cm tall producingflowering and sterile shoots.

Key featuresYoung plant: The backs of the leaves areshiny.

Fruit: The spikes have no awns.

LookalikesPerennial rye-grass may be confused withrough-stalked meadow-grass when young.The flowerhead is similar to common couchbut the spikelets of rye grasses are at 90degrees to the stem while couch spikelets liewith their flattened side next to the stem.

BiologyPerennial rye-grass can become a weed inarable crops where pasture forms part of therotation. The plants remain green all winterand continue to grow. It flowers in early orlate summer. Seeds germinate immediately onshedding, and stems can root.

ManagementControl with glyphosate in fallows, beforebreak crops or as a pre-harvest treatment, orwith specific herbicides within crops. Cleanequipment between fields to reduce seedspread.


PERENNIAL SOW-THISTLE

Perennial sow-thistleSonchus arvensis


WW

142

Geographic locationMainly confined to England and thecoastal areas of Wales, Scotlandand Ireland, perennial sow-thistle isusually found on roadsides andverges and arable field edges.

Soil typeIt prefers damp to wet, heavy deeploams and clays, high in nitratesand humus.




Seeds/head: 160

Seeds/plant: 5000

Lifecycle



Location

Competitive in

seed shed

flowering

germination

unknown

143PERENNIAL SOW-THISTLE

DescriptionIt is a tall prickly perennial which can formlarge clumps, spreading the rhizome. Theleaves are shiny, lobed and green, with anarrow finger-shaped lobe at the tip. Flowersare yellow, similar to dandelion flowers, andarranged in umbrella-like groups.

Key featuresFlower: Typically, the branches of theflowering shoot and the flowerheads beartiny yellow glandular hairs.

BiologyPerennial sow-thistle is a weed of fieldmargins but may occur in patches in arablefields; it is most often a nuisance in perennialcrops. The advent of set-aside encouraged thisweed. The flowers are fertilised by insects andcan be cross- or self-fertile. Seeds aredispersed by wind and germinate in spring,requiring chilling.

ManagementIt is readily controlled in open ground, butcan be awkward to control selectively incrops other than cereals and brassicas.As perennial sow-thistle can also spread fromfragments of rhizomes, autumn cultivation toweaken rhizomes may assist in control.


PINEAPPLEWEED

PineappleweedMatricaria discoides


WW

144

Geographic locationPineapple weed grows in all arablecrops and on compacted soil orhabitats with a wide proportion ofbare ground. It is usually alowland species but has been foundat an altitude of 530m.

Soil typeIt is restricted to damp andnutrient-rich sandy soils and loams,pH >5.




Seeds/head: 50 - 400


Lifecycle



Location

Competitive in

seed shed

flowering

germination

145PINEAPPLEWEED

DescriptionIt is an upright, stiffly branched, bushyannual dicotyledon, 5 - 40cm tall. The leavesare finely divided and feathery. Flowers arelike other mayweeds but lack the white outerpetals.

Key featuresPlant and flower: It smells strongly ofpineapple when bruised.

BiologyPineappleweed is usually found on tracks andin gateways, but also encroaches onto arableland, preferring compacted soils. It is found inboth winter and spring crops and can becomea nuisance in perennial crops where there is alot of vehicle movement. Seedlingsgerminating in autumn can overwinter.Spring-germinating plants can set seed within40 to 50 days. Seeds are usually dispersed onboots and tyres.

ManagementIt is readily controlled with herbicides and in-crop cultivation.


POTATO

PotatoSolanum tuberosum


WW

146

Geographic locationPotato usually occurs as volunteersfrom previous cropping and so ismost likely to be found in thearable areas to the east of theBritish Isles. It also grows in areaswhere domestic waste has been left.

Soil typePotato prefers sandy loams, siltloams, loams and peat soils.


Lifecycle



Location

Competitive in

seed shed

flowering

germination

seedvolunteers

seedvolunteers

147POTATO

DescriptionIt is an upright dicotyledon up to 1m high,with stolons developed into tubers at or justbelow the soil surface. It is very robust, withleaves divided in oval leaflets. Flowers arewhite or purple. The plant may develop largespherical poisonous fruits that resemble greentomatoes.

Key featuresIt contains the poison solanine, in the greenparts of the plant and in tubers exposed tolight, which can be fatal to humans andlivestock.

BiologyVolunteer potatoes can be very competitiveweeds in subsequent crops. They developfrom tubers left in the soil, or as seedlingsfrom true seeds in spring.

ManagementThe best control is good harvesting practice inpotato crops. In cereal crops, sulfonylureashave an effect in reducing further tubergrowth. Pre-harvest treatment with glyphosateis effective if the plants are still green. In most vegetable crops, fruit crops andlegumes only physical control is possible.Otherwise using glyphosate at or nearflowering of potato plants is the mosteffective chemical treatment. Potatoes do notpersist in dense crops such as oilseed rapeor grassland.

PRICKLY SOW-THISTLE

Prickly sow-thistleSonchus asper


WW

148

Geographic locationPrickly sow-thistle inhabits a widevariety of lowland places includingverges, waste ground, railway lines,field margins of arable fields andgardens.

Soil typeIt likes nitrogen-rich loams ornutrient-rich sandy and stony soilswhich are not too dry.




Seeds/head: 100

Seeds/plant: 5000

Lifecycle



Location

Competitive in

seed shed

flowering

germination

149PRICKLY SOW-THISTLE

DescriptionIt is an upright annual dicotyledon growing to120cm. Flowers are pale yellow in looseclusters.

Key featuresPlant: The glossy leaves are a rich green andhave sharp prickly edges and rounded baseswhich clasp the stem.

Leaves: The petals are red grey underneath.

BiologyPrickly sow-thistle is less common on arableland than it once was. It occurs mainly invegetable crops, but can be found in cerealsand increasingly in other winter crops. Plants which germinate in autumn overwinteras rosettes, producing flowers in May; plantsgerminating in spring flower in June. The latter can set seed in 10 weeks. Prickly sow-thistle only reproduces by seedand is distributed by wind.

ManagementIn row crops, hoeing can be used for controlwhere herbicides are not available. In wintercereals, use fallows to reduce seed production.Prickly sow-thistle does not persist in grassyrotations.


RAGWORT

RagwortSenecio jacobaea


WW

150

Geographic locationRagwort is commonly found ongrasslands and neglected land,headlands and verges. Growing toan altitude of nearly 700m.

Soil typeIt grows in a wide range of soils,between pH5 and 7.

Seed longevity: >5years

Seed weight: 0.2 mg

Seeds/head or capsule: 100

Seeds/plant: 50 000 - 60 000

Lifecycle



Location

Competitive in

seed shed

flowering

germination

151RAGWORT

DescriptionIt is a medium-tall, hairless biennial, not verybranched, with a basal rosette of grey-green,roundly divided leaves. The flowerhead hasgroups of yellow daisy-like flowers.

Key featuresPlant: The plant contains the poisonJacobine, which is fatal to livestock.

BiologyRagwort can be abundant in poor pastureand wasteland, particularly on sandy free-draining soils. It is rarely found as an arableweed, but does establish in fallows and fieldmargins. Seedlings germinating in autumn canoverwinter as leafy plants. The plant maytake more than two years to flower. Seed isnot dispersed far from the parent plant, butcan survive grazing and can be transported bysheep. The flowering shoots die by winter.

ManagementDense grass swards which are not over-grazedreduce establishment. In grass, MCPA or 2,4-D may be used at full dose on the rosettesin late spring or early autumn.


RED DEAD-NETTLE

Red dead-nettleLamium purpureum


WW

152

Geographic locationRed dead-nettle mainly grows onsites with bare soil, such as arableland, gardens, soil heaps anddemolition sites. It is generally alowland species growing up to analtitude of 300m, but has beenfound at 600m.

Soil typeIt prefers relatively fertile soils,sandy loams with moderate organicmatter and rich in nutrients.


Germination depth: 0.9 mg

Seed weight: 0.9 mg

Seeds/flower: 4


Lifecycle



Location

Competitive in

seed shed

flowering

germination

153RED DEAD-NETTLE

DescriptionIt is a downy, purplish-tinged bushy annualdicotyledon 10 - 40cm tall. The leaves areheart-shaped with toothed edges. The flowersare purplish pink and cluster in conspicuouswhorls round the stem.

Key featuresYoung plant: The first true leaves are moretriangular than those of henbit dead-nettle.

Plant: The foliage is often tinged withpurple.

LookalikesRed dead-nettle may be confused withhenbit dead-nettle; dead-nettles can bedifficult to distinguish at the seedling andyoung plant stages.

BiologyRed dead-nettle is common on arable land; itmay be encouraged by minimal cultivationtechniques. The plants may overwinter withgreen leaves but it is mainly annual. It can setseed before the canopy is developed. Non-flowering shoot tips can also re-root afterspring cultivations and can go on to establishand set seed. Seeds can be locally movedby ants.

ManagementAlthough it occurs in both winter and springcrops, it is more common in early sownwinter crops, suggesting it may be controlledby spring cropping. A large range ofherbicides suitable for broad-leaved weedsmay be used.


RED FESCUE

Red FescueFestuca rubra


WW

154

Geographic locationRed fescue grows over the whole ofthe British Isles in many grassyhabitats such as road verges,meadows and pastures up to analtitude of 1080m. It has manyvarieties.

Soil typeIt grows in alkaline-rich soils andeven rocky habitats, but is notusually found where there is a largeamount of exposed soils.


Seed weight: 1 mg

Seeds/head: 100

Seeds/plant: 10

Lifecycle



Location

Competitive in

seed shed

flowering

germination

155RED FESCUE

DescriptionIt is a densely tufted perennial grass,15 - 90cm tall. It spreads by rhizomes.The leaves are green or greyish-green andbristle-like. The flowerhead tapers to a pointbut is rather one-sided.

Key featuresPlant: Stems are red at the base.

BiologyRed fescue can establish in arable land butdoes not persist with cultivation. It iscommonly found in field edges and manyother relatively undisturbed habitats. Red fescue grows rapidly in spring afteroverwintering. It can also reproducevegetatively when the rhizomes which attachchild plants die.

ManagementIt is relatively tolerant of foliar-actingherbicides because of its bristle-like leavesreducing uptake, so high doses are generallyrequired.


REDSHANK

RedshankPersicaria maculosa


WW

156

Geographic locationRedshank is a lowland weedgrowing to an altitude of up to200m. It is found on disturbed baresoils, such as arable land and soilheaps.

Soil typeIt is found on a wide range of soiltypes but prefers sandy soils rich innutrients and organic matter andwell aerated, in the pH range 5 - 7.




Seeds/flower: 2 - 4


Lifecycle



Location

Competitive in

seed shed

flowering

germination

157REDSHANK

DescriptionIt is a sprawling hairless annual which mayhave an upright stem. It has dark spottedtapering leaves. The flower spike is small butdense with pink flowers. The loose sheathsover the leaf stem base have long hairs.

Key featuresPlant: The stem is hairless and the leaveshave a characteristic blotch.

Flowers: The flowering spike is less densethan that of pale persicaria.

LookalikesRedshank may be confused with palepersicaria: pale persicaria has silvery hairson the first true leaves, but redshank is nothairy. The first leaf of redshank is broad butthat of pale persicaria is long and narrow.

BiologyRedshank is a common weed of spring crops.Seeds are retained on the plant and cancontaminate grain at harvest. Duringcultivations plant fragments can root at thenodes. Plants are frost susceptible.

ManagementRedshank is controlled by a range ofhormonal and sulfonylurea herbicides incereals and by many residual herbicides inmost spring sown-crops.


ROUGH-STALKED MEADOW-GRASS

Rough-stalked meadow-grassPoa trivialis


WW

158

Geographic locationRough meadow-grass occurs indamp, fertile and sometimesdisturbed land with large amountsof bare soil. It is most frequent inlowland areas but has beenidentified at an altitude of 760m.

Soil typeIt grows on all but the most acidicsoils but is usually found at pH> 5.It prefers moisture-retentive soils.



Seeds/head: 1 - 10

Lifecycle

Location



Competitive in

seed shed

flowering

germination

159ROUGH-STALKED MEADOW-GRASS

DescriptionIt behaves like an annual in cereal crops orcan grow as a semi-rosette with creeping leafystolons. Stems may reach 90cm, but areusually prostrate. The leaf blade is foldedwith a curved tip. The flowerhead is a conicalshape.

Key featuresPlant: The leaf sheath is rough and thelower leaf surface is glossy with aprominent ridge.

BiologyRough meadow-grass is palatable to stockand is useful for hay. It tends to flower inwinter cereals, but spreads by stolons anddoes not produce flowerheads in springcereals. Although plants can overwinter theydo not grow before April. Growth in spring isfast, but leaves are short-lived. Seedlingsgenerally germinate immediately after seedsare shed, although some remain dormant.Vegetative reproduction can also occur fromstolon fragments.

ManagementPloughing reduces populations so that plantstend to be more frequent in minimum tillage.A wide range of herbicides is available forcontrolling rough meadow-grass. Although itis harder to control than annual meadow-grass, some residual grass herbicides arereasonably effective. In winter rape,propyzamide and carbetamide are alsoeffective.


ROUND-LEAVED FLUELLEN

Round-leaved fluellenKickxia spuria


WW

160

Geographic locationRound-leaved fluellen is a lowlandspecies which often grows with thesharp-leaved species in cornfieldsand other arable fields and gardens.

Soil typeIt likes weakly acid to weaklyalkaline soils low in nutrients,including light soils over boulderclay. It prefers light conditions.



Seeds/flower: 25

Seeds/plant: 2000

Lifecycle

Location



Competitive in

seed shed

flowering

germination

161ROUND-LEAVED FLUELLEN

DescriptionIt is a sprawling dicotyledon, growing to20 - 40cm, with glandular hairs.

Key featuresYoung plant: The first true leaves arerounder than those of sharp-leaved fluellen.

Plant: The leaves are almost circular.

Flowers: The flowers resemble those ofsnapdragon and are bright yellow with abrown upper lip.

LookalikesRound-leaved fluellen is difficult todistinguish from sharp-leaved fluellen: the cotyledons are smaller and rounderwhile the first true leaves are also rounder.

BiologyRound-leaved fluellen needs warmerconditions than sharp-leaved fluellen so it ismore common in southern Britain. It is apoorly competitive species found inuncompetitive crops, particularly perennialand row crops. Seeds germinate in spring andset seed usually after harvest. Plants oftengrow lower than the combine cut, so can setseeds in late-ploughed fields.

ManagementIt is readily controlled by cultivation andseldom found in competitive winter crops orgrass ley rotations.


RYE BROME

Rye bromeBromus secalinus

Value to BiodiversityResistanceSpring CropsWOSR��

WW

162

Geographic locationRye brome is a lowland weed,found in cereal fields, and wasteground and some improved leys.

Soil typeIt is usually found in areas on soilswith average moisture andreasonable but not high nitrogen,pH about 5.




Lifecycle

Location



Competitive in

seed shed

flowering

germination

unknown

163RYE BROME

DescriptionIt is a rather variable robust annual grass withstems usually 50 - 100cm tall. Leaf bladeshave rough surfaces and are pointed.

Key featuresFlower: The leaf sheaths are usually hairlessor the lower ones can be sparsely hairy.

Flowers/fruit: It has flattened spikelets withshort awns.

BiologyRye brome was most probably introduced tothe UK as a contaminant of cereal seeds. It was once grown as a grain crop and wasvery common as a weed in the past, oftendominating fields of wheat. With improvedmethods of cereal grain cleaning, it is nowuncommon to rare, generally found inheadlands of winter-sown crops. It propagatesonly by seed and can be found in large patches.

ManagementShed seed should be kept on the surface for 4weeks before cultivation to allow ripening andkilled with a glyphosate application beforesowing subsequent crops. Deep cultivations ormouldboard ploughing, to bury seeds below20cm, will reduce numbers in following years.Spring cropping is effective for control, as isfallow land, as long as emerging plants arecontrolled before setting seed.



SCARLET PIMPERNEL

Scarlet pimpernelAnagallis arvensis


164

Geographic locationScarlet pimpernel is a commonannual weed of cultivated andwaste ground with a widespreaddistribution in arable soils andsome semi-natural habitats.The blue form prefers south-facingslopes.

Soil typeIt grows in many soil types withneutral pH in partial shade to sun.


Seed weight: 0.5 mg



Lifecycle

Location



Competitive in

seed shed

flowering

germination

165SCARLET PIMPERNEL

DescriptionIt is a slender, hairless annual dicotyledonwith prostrate, sprawling or upright four-angled stems, 5 - 50cm long. The flowers arebright scarlet. There is a rare form of scarletpimpernel with bright blue flowers.

Key featuresYoung plant/plant: There are tiny browndots on the undersides of the leaves. Allparts are poisonous to poultry and stock.

Flowers: The flowers tend to open in fullsunlight and remain closed on dull orrainy days.

LookalikesScarlet pimpernel may be confused withcommon chickweed: the seedlings aresimilar but chickweed seedlings have a longhypocotyl. The leaves of chickweed havehairy stalks and are light green, while theunderside of scarlet pimpernel leavesis spotted.

BiologyScarlet pimpernel occurs frequently in spring-sown crops. Seed is widely dispersed as aresult of agricultural management,particularly as a contaminant of crop seed.Scarlet pimpernel is often associated withrarer arable weeds. Plants regenerate by seedwhich requires light for germination. Plantscan overwinter and summer-shed seeds cangive rise to a second generation.

ManagementControl by using a stale seedbed.


SCENTED MAYWEED

Scented mayweedMatricaria recutita

Value to BiodiversityResistanceSpring CropsWOSR��

WW

166

Geographic locationScented mayweed is a lowland plantor arable cereal fields and wasteplaces.

Soil typeIt is usually found on light soils,but also occurs on heavy clays andloams.



Seed weight: 0.1 mg

Seeds/plant: 5000

Lifecycle

Location



Competitive in

seed shed

flowering

germination

167SCENTED MAYWEED

DescriptionIt is a branching annual dicotyledon, 60cmtall, with feathery finely divided leaves.The flowers resemble those of daisies.

Key featuresFlowers: The flowerheads give off adistinctive chamomile smell when crushed.When the flowerhead is split, the end of thestem where the petals are attached is hollow.

LookalikesScented mayweed may be confused withscentless mayweed. The mayweeds aredifficult to distinguish in their non-flowering stages.

BiologyScented mayweed is locally abundant on arableland and causes yield loss in cereals and oilseedrape. It emerges in winter and early spring; ifgerminating in autumn, it overwinters as arosette. It infests both winter and spring crops,which makes long-term management withoutherbicide difficult. The seedbank can surviveshort-term grass leys.

ManagementA wide range of herbicides is available forscented mayweed control in wheat and as yetno herbicide resistance has been identified inthis species though it has been suspected inother Matricaria species.


SCENTLESS MAYWEED

Scentless mayweedTripleurospermum inodorum

Value to BiodiversityResistanceSpring CropsWOSR� � � � �WW

168

Geographic locationScentless mayweed is mainly alowland species growing to amaximum altitude of 500m, in openhabitats such as arable soils and lessfrequently other disturbed sites.

Soil typeIt prefers warm, fertile and heavysoils with pH>4.5 and preferably>5.5.



Seed weight: 0.3 mg

Seeds/flowers: 1

Seeds/plant: 10 000 - 200 000

Lifecycle

Location



Competitive in

seed shed

flowering

germination

169SCENTLESS MAYWEED

DescriptionIt is a much-branched annual dicotyledon,10 - 80cm tall, with finely divided featherygreen leaves. Scentless mayweed often sprawlsalong the ground but may be more uprightwhen supported by a crop.

Key featuresFlowers: Scentless mayweed flowers are flator convex. When the daisy-like flowerheadis split, the end of the stem to which thepetals attach is solid.

LookalikesScentless mayweed may be confused withscented mayweed: the mayweeds aredifficult to distinguish in their non-flowering stages.

BiologyScentless mayweed is the most widespread ofthe mayweeds found on arable land. It canbe a problem in both winter- and spring-sowncrops. It is competitive in wheat and oilseedrape and the seeds can clog sieves andcontaminate grain samples.

Plants of scentless mayweed can overwinterfrom later germination. Newly emerged plantsare fairly slow-growing. It reproduces fromseed moved by humans, birds or stock.

ManagementScentless mayweed can be controlled by awide range of herbicides, but because of itslong period of emergence it may needrepeated treatments.

Populations resistant to 2, 4-D have occurredin cereal crops in the UK.


SHARP-LEAVED FLUELLEN

Sharp-leaved fluellenKickxia elatine


WW

170

Geographic locationSharp-leaved fluellen is found inarable fields, field margins, gardensand waste ground.

Soil typeIt likes weakly acid to weaklyalkaline soils, including light soils,over boulder clay. It can toleratepoorly aerated soils as it is shallow-rooted, but prefers fairly lightconditions.


Seed weight: 0.4 mg

Seeds/flower: 17

Seeds/plant: 1800

Lifecycle

Location



Competitive in

seed shed

flowering

germination

171SHARP-LEAVED FLUELLEN

DescriptionIt is a hairy, leafy, annual dicotyledon,creeping to 50cm, or weakly upright.

Key featuresPlant: The leaves are arrow-shaped withbackward-pointing lobes.

Flower: The flowers are like smallsnapdragon flowers, yellow with a purpleupper lip.

LookalikesSharp-leaved fluellen may be confused withround-leaved fluellen, although thecotyledons are more oval and notched atthe tip, and the first true leaves end in bluntpoints.

BiologySharp-leaved fluellen is a poorly competitivespecies found in uncompetitive crops: it ismost successful in perennial crops and rowcrops. It is seldom found in competitivewinter crops or grass ley rotations. Seedsgerminate in spring and set seed usually afterharvest. Plants often grow lower than thecombine cut, so can set seeds in late-ploughedfields.

ManagementIt is readily controlled by cultivations.


SHEPHERD’S NEEDLE

Shepherd’s needleScandix pecten-veneris


172

Geographic locationShepherd’s-needle is a rare lowlandweed, found up to an altitude of320m, growing in cultivated areassuch as old or current arable landand gardens.

Soil typeIt likes warm, preferably chalkyclay soils which are dry in summerand nutrient-rich.


Seed weight: 20 mg

Lifecycle

Location



Competitive in

seed shed

flowering

germination

173SHEPHERD’S NEEDLE

DescriptionIt is a short, almost hairless annual, growing upto 30cm tall, with finely divided and subdividedleaves. When supported by the crop it maygrow to 60cm. The flowerheads are groups ofup to ten tiny white four-petalled flowers.

Key featuresYoung plant: The cotyledons are pointed andvery long.

Flowers: As the fruits mature and extend, theflowers appear to be on top of ‘needles’.

LookalikesShepherd’s-needle may be confused with wildcarrot as young plants: the first true leaves ofwild carrot are hairy and coarser than thoseof shepherd’s-needle, which has few hairs.Shepherd’s-needle cotyledons are much longerand thinner than those of wild carrot.

BiologyShepherd’s-needle is highly competitive in springcereal crops and open crops of winter wheat,even when high levels of nitrogen are applied. Ithas re-appeared in some areas of the country inthe last few years, preferring light soils. It canreduce combine efficiency when the stems andlong seeds can become trapped. Shepherd’s-needle reproduces only by seed. Seeds aredispersed mechanically from the parent plantand can also hook onto hair or clothing.

ManagementThe re-appearance of shepherd’s-needle incereals may be due to the reduction in the useof 2, 4-D and MCPA at high doses, butcombinations of sulfonylureas with contactherbicides and hormones can be effective.


SHEPHERD’S-PURSE

Shepherd’s-purseCapsella bursa-pastoris


174

Geographic locationShepherd’s-purse is usually alowland weed but may grow to analtitude of 400m. It is found ondisturbed, especially fertile ground,with areas of bare soil and is usuallyassociated with broad-leaved cropsrather than cereal crops.

Soil typeIt generally grows in nutrient-richsoils, with pH>5, such as humus-richloams and nitrate-rich sandy soils.Shepherd’s-purse avoids wet soils.


Seed decline: 22-36% per year



Seeds/flower: 30

Seeds/plant: 2000 - 40 000

Lifecycle

Location



Competitive in

seed shed

flowering

germination

175SHEPHERD’S-PURSE

DescriptionIt is a very variable annual or biennialdicotyledon, growing to 5 - 60cm. Most ofthe leaves grow as a rosette at the base.The flowerhead is covered with small fourpetalled white flowers, developing into acharacteristic heart-shaped seed head.

Key featuresYoung plant: The hairs on the young leavesare unbranched (a hand lens is required).

LookalikesAs it is so variable, shepherd’s-purse canresemble several other species, particularlyearly stages of common poppy. Note thesimple unbranched hairs of shepherd’s-purse.

BiologyShepherd’s purse is widespread in crops in allseasons in the UK and throughout most of theworld. It is more of a problem in oilseed rapeor other brassica crops, so this weed should becontrolled in the cereal crop. Germination canoccur throughout the year and plants are ableto overwinter. Plants have a short life span.The sticky-coated seeds may be transported onfootwear or agricultural machinery.

ManagementIt is susceptible to a wide range of herbicides.


SMALL NETTLE

Small nettleUrtica urens


WW

176

Geographic locationSmall nettle is found up to analtitude of 500m on well-cultivatedarable land, especially in leaf cropsas it germinates in spring, and ingardens, farmyards and othercultivated soils.

Soil typeIt likes well-drained neutral soilshigh in nitrogen.


Seed weight: 0.4 mg

Seeds/flower: 1


Lifecycle

Location



Competitive in

seed shed

flowering

germination

177SMALL NETTLE

DescriptionIt is an annual dicotyledon, 10 - 60cm tall.The plant is compact in habit, with dark-green pointed toothed leaves, covered instinging hairs.

Key featuresPlant: The leaves are rounder and morepointed and toothed than those of commonnettle.

Flower: The male and female flowersare borne on the same plant in littleclusters close to the stems.

BiologySmall nettle is more common in broad-leavedcrops than in cereals and in spring rather thanwinter crops. It is poorly competitive invigorous cereal crops. Plants are susceptible tofrost but seeds can germinate at lowtemperatures and plants can overwinter insheltered areas. Seeds can be transported byingestion by animals or in soil. The seedbankis persistent.

ManagementSmall nettle can be controlled by a wide rangeof herbicides in cereal crops. It is susceptibleto hoeing in row crops.


SMOOTH SOW-THISTLE

Smooth sow-thistleSonchus oleraceus


WW

178

Geographic locationGrowing to an altitude of 365m,smooth sow-thistle is found onarable fields, verges, roadsides,gardens, waste lands and manureheaps.

Soil typeIt likes nitrogen-rich loams ornutrient-rich sandy and stony soilswhich are not too dry.




Seeds/head: 100

Seeds/plant: Up to 100 000

Lifecycle

Location



Competitive in

seed shed

flowering

germination

179SMOOTH SOW-THISTLE

DescriptionIt is a branched and upright annualdicotyledon, 30 - 120cm tall, sometimestinged with red or purple. The yellow flowersare flask-shaped and grow in loose clusters.

Key featuresPlant: The leaves are glossy and softlyprickly with a wide triangular lobe atthe tip, clasping the stem.

BiologySmooth sow-thistle is increasing in arablerotations, particularly in winter crops.Autumn-germinating plants can overwinter asrosettes and flower in May; spring-germinatingplants flower in June.

ManagementIn row crops, hoeing is an alternative toherbicide use. Control in uncropped land toreduce seed return. Smooth sow-thistle doesnot persist in grassy rotations. There is a widerange of herbicides available for control incereal crops.


SOFT BROME

Soft bromeBromus hordeaceus


180

Geographic locationSoft brome prefers disturbed, dampand grassy habitats, but is notfound in waterlogged ground. Itusually grows at altitudes of up to400m.

Soil typePrefers neutral to alkaline soils,pH>5.

Seed weight: 5 mg

Seeds/head: 100

Lifecycle

Location



Competitive in

seed shed

flowering

germination

181SOFT BROME

DescriptionIt is a tufted annual grass which hybridiseswith related species. It grows to a height of10 - 100cm. Mature plants have dense softhairs on the leaf sheaths. The leaf blades aregreyish-green and the flowerhead is uprightand compact.

Key featuresPlant: The stems are very hairy and moreupright than those of meadow brome.

BiologySoft brome is found in grass and arable cropsand field margins and is often a contaminantin rye and fescue seeds. Seeds germinaterapidly in autumn and young plants can growrapidly in cooler months; plants may remaingreen over winter. Vegetative growth occurs inautumn and spring. Compact flowerheadsoccur in early summer.

ManagementShed seed should be kept on the surface for4 weeks before cultivation to allow ripeningand killed with a glyphosate applicationbefore sowing subsequent crops. Deepcultivations or mouldboard ploughing, to bury seeds below 20cm, will reducenumbers in following years. Spring croppingis effective for control, as is fallow land, aslong as emerging plants are controlled beforesetting seed.



SPEAR THISTLE

Spear thistleCirsium vulgare


WW

182

Geographic locationSpear thistle is found all over theBritish Isles up to an altitude of850m, in many habitats includinghedgerows, field margins pasturesand arable fields.

Soil typeIt prefers fertile and well-draineddisturbed soils.


Seed weight: 2.5 mg

Seeds/head or capsule: 100

Seeds/plant: 8000

Lifecycle

Location



Competitive in

seed shed

flowering

germination

183SPEAR THISTLE

DescriptionIt is a biennial dicotyledon, usually 30 - 150cmtall, though occasionally taller. It is very spinyand has a very deep tap root. The thistleflowers are reddish purple and usually occursingly on the flower stalk.

Key featuresPlants: The stems have spiny wings and theyoung leaves have a hairy upper surface.

LookalikesSpear thistle may be confused with creepingthistle; the young plants of thistles are oftendifficult to tell apart. Spear thistle has alarge and densely hairy leaf second,creeping thistle has fewer marginal spines.

BiologySpear thistle is common in arable fields.The plant dies in the autumn after flowering.It reproduces only from seeds, which havelittle dormancy and germinate in autumn orspring; the immature plants can overwinter asa rosette. Most of the seeds (up to 93%) areeaten by birds or small mammals.

ManagementBeing a biennial, it does not persist in arablerotations or routinely cultivated soils, but isencouraged by fallow or grass breaks orperennial crops. Seedlings are controlled byharrowing. Established plants are not easilycontrolled by mechanical means. MCPAherbicides can be used in cereal crops.


SPREADING HEDGE-PARSLEY

Spreading hedge-parsleyTorilis arvensis


184

Geographic locationSpreading hedge-parsley is found inlowland areas, usually in fieldmargins and late-sown crops or inwaste and disturbed ground. It isincreasingly rare and geographicallyisolated in small pockets in thesouth of England.

Soil typeIt is found on chalky clay soils oflow moisture and fertility but cangrow on sands and gravels.

Seed longevity: Short lived

Lifecycle

Location



Competitive in

seed shed

flowering

germination

�

185SPREADING HEDGE-PARSLEY

DescriptionIt is a much-branched hairy annual thatgrows close to the ground, 10 - 20cm tall.The leaves are feathery like those of carrot,divided into three separate leaflets which arefurther divided. The small white flowers arein little clusters of 3 to 5. The fruit is coveredwith hooked spines.

Key featuresYoung plant: It is slightly hairy.

Plant: The stem is finely grooved.

BiologySpreading hedge-parsley germinates inautumn, suggesting that the seed is short-lived. The fruit is transported by hooking onto fur or clothing.

ManagementSpreading hedge-parsley is not competitive tomodern crops, and its late floweringdisadvantages it in early-harvested and early-ploughed crops.


SUGAR BEET

Sugar beetBeta vulgaris


186

Geographic locationSugar beet is found usually inlowland areas as a volunteer fromprevious cropping.

Soil typeIt is found on light arable soils.

Seeds/flower: 1

Seeds/plant: 10 000

Lifecycle

Location



Competitive in

seed shed

flowering

germination

187SUGAR BEET

DescriptionIt is a large biennial that grows to 1.8mtall, but in the first year has a rosette oflarge dark-green oval leaves. The cultivatedform of beet has a large tap root.

Key featuresFruit: It is distinguished from other beets bythicker leaves and a large bulbous tap root.

BiologyWeed beet are any unwanted sugar beetgrowing within and between the rows ofsown beet, or other crops. They grow fromgroundkeepers or from seed shed by boltingcrop plants, or other weed beets. As seedlings,they are indistinguishable from sugar beet.Sugar beet which germinates in spring usuallyoverwinters as a leafy rosette before floweringin the following year. However in some casesthe plants flower in the first year (in a cropthese beets are known as bolters) and areprolific seed producers.

ManagementCrops containing bolters should be harvestedas early as possible to reduce the productionof viable seeds. The sulfonylurea group ofherbicides is particularly active on weed beet.

SUNFLOWER

SunflowerHelianthus annuus


WW

188

Geographic locationSunflower grows mostly in theMidlands and south of England,mainly as a volunteer from previoussunflower crops, bird-seed etc., onwasteland and banks.

Soil typeIt requires nutrient-rich and moistsoils to grow.


Seeds/plant: <1 year

Lifecycle

Location



Competitive in

seed shed

flowering

germination

189SUNFLOWER

DescriptionIt is a sturdy annual dicotyledon, growing1 - 3m tall. At all stages the plant is verylarge, with sturdy stems and large bright,yellow flowers.

Key featuresFlowers: Flowerheads face the sun andsometimes track it. They dip as they ripen.

BiologySunflower seeds germinate in late spring andplants flower and set seeds in the samegrowing season. The seeds are eaten by birdsand small mammals.

ManagementAlthough it may occur as a volunteer in thetwo years following a crop it rarely persistsfor longer. It is easily cleaned out from mostother crop seeds. It is controlled by a range ofherbicides suitable for broad-leaved crops.


TIMOTHY

TimothyPhleum pratense


WW

190

Geographic locationTimothy is found in a range ofgrasslands including meadows andrough grassland up to an altitude of450m.

Soil typeIt prefers heavy slightly damp soils.


Seed weight: 0.5 mg

Seeds/flower: 1

Lifecycle

Location



Competitive in

seed shed

flowering

germination

191TIMOTHY

DescriptionIt is a coarse tufted grass growing to 150cmtall. Leaves are pale green and pointed. The flowerhead is packed with tiny spikeletsso it looks smooth like fur.

Key featuresPlant: The plants have an upright habit.

BiologyTimothy is a common component of pasturesand other sown grassland and can be found incereal crops in grassy rotations. Timothyemerges from both seed and tussockfragments. Tillering occurs in spring andautumn and stems remain green over winterand grow in the spring; a second period ofgrowth may occur in July.

ManagementIn winter cereals, some control withherbicides may be possible. It does not persistinto spring crop breaks or if soils areroutinely cultivated.


VENUS’S-LOOKING-GLASS

Venus’s-looking-glassLegousia hybrida


WW

192

Geographic locationVenus’s-looking-glass is a lowlandweed found in arable fields, or ondisturbed soils such as motorwayembankments.

Soil typeIt prefers chalky soils and low-nitrogen conditions.



Seeds/flower: 40

Lifecycle

Location



Competitive in

seed shed

flowering

germination

unknown

193VENUS’S-LOOKING-GLASS

DescriptionIt is an upright, roughly hairy annualdicotyledon, growing up to 30cm tall. The leaves are wavy with short stalks. It hastubular pink flowers. The ovary starts toextend as the flower becomes fertile and lookslike three touching cylinders.

Key featuresFruit: Only two of the three seed head‘cylinders’ are visible from one side.

BiologyVenus’s-looking-glass can germinate fromautumn through to spring. It is insect-pollinated. It is rarely a problem incompetitive crops but can be found in newlyemerged crops.

ManagementIt does not persist in winter croppingrotations and is readily controlled in earlyspring by cultivation.


WALL SPEEDWELL

Wall speedwellVeronica arvensis


194

Geographic locationWall speedwell grows to an altitudeof 800m and is usually found onarable land, tracks, waste ground,heaths, grasslands and gravelledpaths.

Soil typeIt likes nutrient-rich moderatelyacidic loose loams or sandy loamswith some humus.



Seeds/flower: 15


Lifecycle

Location



Competitive in

seed shed

flowering

germination

195WALL SPEEDWELL

DescriptionIt is a short plant 3 - 15cm tall, branched andstiffly upright with small oval leaves. The stemis hairy. The very small, intensely blue flowersare borne on short stalks in the leaf axils.

Key featuresPlant: The leaves are small and long, oval inshape.

Fruit: It is heart shaped.

BiologyWall speedwell is very common on arableland, particularly in winter cereals, but isnot competitive in vigorous cereal crops.It does not persist in grass leys. Although itcan root from stem fragments, this does notoccur in the field. Seeds shed in the summercan germinate in the following autumn givingrise to overwintering plants, or germinate inthe following spring. Seeds are moved byhumans or cattle or air currents.

ManagementWall speedwell does not thrive in dense crops.It is not affected by minimum tillage. Cerealcrops may be harrowed early in the seasonand row crops can be hoed.

It can be controlled by a range of herbicidessuitable for broad-leaved weeds in cereal crops.


WHEAT

WheatTriticum aestivium


196

Geographic locationWheat grows as volunteers insubsequent crops, so tends to befound in arable areas.

Soil typeIt prefers a soil which holds togetherwell with good water retention. Itlikes a high nitrogen input.

See longevity: 1 year

Seed weight: 55 mg

Seeds/ear: 40 - 50


Lifecycle

Location



Competitive in

seed shed

flowering

germination

� �

197WHEAT

DescriptionIt is an annual tufted grass which may growup to 1.2m in short-strawed varieties or 1.8min long-strawed. It has hollow or pithy stemswith flat broad leaves and a stiff appearance.The flower spike appears square in crosssection.

Key featuresFruit: It has large grains.

BiologyVolunteer wheat can occur as a weed in thesubsequent crop. It can germinate in earlyautumn or spring and has one generation ayear. It seldom persists for more than oneseason if controlled; seed buried for two yearsis unlikely to remain viable.

ManagementWhere wheat seeds have been shed duringharvest, light harrowing will encouragegermination, to allow control before sowingthe next crop. Wheat cannot be controlled byherbicides in other cereals but a wide range ofherbicides can control wheat in other crops.


WHITE CAMPION

White campionSilene latifolia


198

Geographic locationWhite campion grows to an altitudeof 425m and is found on arablefields, waste ground and roadverges.

Soil typeIt prefers deep well-drained soils.



Seed weight: 7.3 mg

Seeds/flower: 230

Seeds/plant: 6000

Lifecycle

Location



Competitive in

seed shed

flowering

germination

199WHITE CAMPION

DescriptionIt is a softly hairy, biennial or short-livedperennial dicotyledon, 30 - 100cm tall. The leaves are pointed and reasonably broad.Male and female flowers are white with fivedeeply notched petals.

Key featuresYoung plant: First true leaves are bluntlypointed.

Flowers: White, deeply notched petals.

BiologyWhite campion is common on arable land,emerging largely in spring crops, but it canpersist to produce large plants inperennial/biennial crops. About half ofoverwintering adult plants can survive ahard winter.

ManagementIt is seldom a problem in winter rotations, orwhere there are grass ley breaks. Large plantscan be pulled in some crops, or cut beforeflowering to prevent seeding.


WILD CARROT

Wild carrotDaucus carota


WW

200

Geographic locationWild carrot is found up to analtitude of 400m in England andthe warmer coastal areas ofScotland, Wales and Ireland. It prefers disturbed or wasteground, or open turf on chalkydownland.

Soil typeIt prefers infertile but well-drainedchalky soils.


Seed weight: 1 mg

Seeds/floret: 2

Seeds/plant: 1000 - 40 000

Lifecycle

Location



Competitive in

seed shed

flowering

germination

201WILD CARROT

DescriptionIt is usually a biennial or short-lived perennialdicotyledon, though it can also flower in thefirst year. It grows up to 80cm tall. The basalrosette leaves are hairy and coarsely divided,with triangular leaf stalks. The flatflowerheads are densely packed with whiteflowers.

Key featuresPlant: It smells of carrot when bruised. The flowering stem appears to zigzag.The buds and dried flowerheads arecup-shaped.

LookalikesWild carrot may be confused withshepherd’s-needle as young plants: the firsttrue leaves of wild carrot are hairy andcoarser than shepherd’s-needle which hasfew hairs.

BiologyWild carrot is usually found in field marginsand seldom encroaches far into arable land,but it can be a problem in perennial crops.It reproduces by seed. Autumn-germinatingplants remain green overwinter. The floweringstem dies in the autumn while often retainingseed. It is capable of interbreeding withcultivated carrot.

ManagementIt does not persist where there is routinecultivation. Herbicides are available for use incereal crops.


WILD-OAT

Wild-oatAvena fatua


202

Geographic locationWild-oat is found mainly to thesouth of Northumberland and inScottish arable areas. It is a grass oflowland areas but it can grow up toan altitude of 300m.

Soil typeIt prefers highly fertile, moist andweakly acid to weakly alkaline soils.



Seed weight: 30 mg

Seeds/spikelet: 2


Lifecycle

Location



Competitive in

seed shed

flowering

germination

203WILD-OAT

DescriptionIt is a tall, stout, annual tufted grass. The leafblade is broad and flat with an anti-clockwisetwist. The flowerhead is spreading with droopingspikelets.

Key featuresPlant: The leaf margins are hairy towards thebase.

Fruit: There is a tuft of tawny hairs at the base,When ripe, the spikelets break apart with visiblescars.

LookalikesAll the oat species are difficult to tell apart at theseedling stage. It is difficult to tell the differentoats apart as plants: winter wild-oat germinatesin the autumn while wild-oat usually germinatesin spring. The leaf margins of wild-oat are hairiernear the base and the spikelets are smaller thanthose of winter wild-oat. The lemmas of wild-oatare broader than those of winter wild-oat andend in two small teeth. These two species areeasiest to tell apart when the fruit is ripe. Wild-oat seeds separate in the spikelet with no scar.

BiologyWild-oats reproduce only from seed. Althoughsome germinate in autumn, tiller in early springand are resistant to frost, most germinate in thespring. One wild-oat plant per square metre canreduce yields by up to 1 t/ha in winter cereals andup to 0.6 t/ha in spring cereals.

ManagementIt is cheaper to control wild-oat in break crops.Delay cultivation as long as possible after harvestto allow mice and birds to eat the freshly shedseeds. Burial will increase seed dormancy. Handrogueing is possible. Clean the combine betweenfields to prevent seeds being spread.


WILD PANSY

Wild pansyViola tricolor


WW

204

Geographic locationWild pansy can grow to an altitudeof 575m and is found in slightlyacidic habitats and cultivatedground, gardens and wasteland. It is most often found in damp coolclimates.

Soil typeIt grows on sandy, stony andinfertile soils, pH range 5 - 7.


Seed weight: 0.4 mg

Lifecycle

Location



Competitive in

seed shed

flowering

germination

205WILD PANSY

DescriptionIt is an annual or perennial dicotyledon,larger and more robust than field pansy.Leaves are oblong, lobed or toothed withprojections at the base. The flowers are five-petalled and blue violet with the lower petalsflushed with bright yellow.

Key featuresPlant: Wild pansy is larger and more robustthan field pansy.

Flowers: The petals are larger than thesepals.

BiologyWild pansy is less commonly seen in fieldsthan field pansy. It is found on stony arableland in both winter and spring crops; seedsmay contaminate grain and be difficult toclean. Wild pansy is not as competitive asfield pansy, but has a similar life cycle;autumn-germinating plants can overwinterand flower early in the following season. The seeds are dispersed from an explodingseed head.

ManagementResidual herbicide treatments are generallyeffective in autumn and spring sown crops.

WILD RADISH

Wild radishRaphanus raphanistrum


WW

206

Geographic locationWild radish is found in arablefields, waste ground and paths upto an altitude of 380m.

Soil typeIt prefers lime-free but nutrient-richsandy and loam soils.




Seeds/head: 3 - 10

Seeds/plant: 160

Lifecycle

Location



Competitive in

seed shed

flowering

germination

�

207WILD RADISH

DescriptionIt is an annual, growing to 1m tall, withroughly hairy stems. The leaves have toothedlobes near the stem and a large lobe at the tip.There is a branched tap root.

Key featuresPlant: The teeth on the edges of the upperleaves are blunt.

Fruit: The pod appears beaded as it shrinksaround the seeds. It has a long beak andbreaks easily at the joints.

LookalikesIt is similar to charlock, as bothhave roughly hairy stems.

BiologyWild radish, also called runch, is one of thecommonest weeds worldwide. It emergesmostly in spring and therefore in spring crops,but it germinates also in early-sown winteroilseed rape. These autumn-germinatingseedlings are generally killed by frosts but canpersist in a mild winter. The seed can betransported as a seed contaminant and canremain viable in manures. Statutory seedregulations for the UK and for England(2002) specify that the seeds must not befound in cereal grain samples. It is aparticular problem in oilseed rape cropswhere the seed cannot be separated.

ManagementWild radish is controlled by residualherbicides, hormones and sulfonylureas incereals and residual herbicides in most springcrops. However it is very difficult to controlin brassica crops.


WINTER WILD-OAT

Winter wild-oatAvena sterilis


208

Geographic locationThe range of winter wild-oat hasgrown from its focus inOxfordshire into East Anglia andthe Midlands. It is a lowland plantfound on waste ground.

Soil typeIt grows on heavy clay soils.



Lifecycle

Location



Competitive in

seed shed

flowering

germination

209WINTER WILD-OAT

DescriptionIt is a tall, stout, annual grass similar tocultivated oat. The leaf blade is broad and flatwith an anti-clockwise twist. The flowerheadis spreading with drooping spikelets.

Key featuresFruit: Winter wild-oat has a narrowerlemma than that of wild-oat and a shorterawn. The seeds are joined in the spikeletand require pressure to prize apart, leavinga scar.

LookalikesAll oat species are difficult to tell apart atboth seedling and adult stages: winter wild-oat germinates in the autumn whilst wild-oat usually germinates in the spring. Wildoat differs from winter wild-oat in thefollowing areas; leaf margins are hairiernear the base, spikelets are smaller, lemmasare broader and end in two small teeth. Thetwo species are easier to tell apart whenripe, wild-oat seeds separate from thespikelet with no scar.

BiologyWild-oat reproduces only by seed; itgerminates in autumn and persists overwinter. One wild-oat plant per square metercan reduce yields by up to 1 t/ha in wintercereals and up to 0.6 t/ha in spring cereals.

ManagementControl is cheaper in break crops; use of staleseedbed in autumn or spring will help. Delaycultivation after harvest to allow seedpredation. Hand roguing is possible whenplants are visible above the crop. Clean thecombine between fields to prevent seeds beingspread.


YORKSHIRE-FOG

Yorkshire-fogHolcus lanatus


WW

210

Geographic locationYorkshire-fog occurs as seedling inevery type of habitat, with thegreatest abundance in meadow andpasture. It can grow at altitudes ofup to 600m. It prefers damp sites,shady areas and low ground. In ditches it can become dominantto the extent of excluding otherspecies.

Soil typeIt grows in a wide range of weaklyacidic soils, preferring moistconditions and high fertility, in thepH range 5 - 7.



Seeds/head: 1 - 10

Lifecycle

Location



Competitive in

seed shed

flowering

germination

211YORKSHIRE-FOG

DescriptionIt is a tufted, very hairy, perennial grass, 20 - 100cm tall, with loose or compactlytufted stems. The plants look velvety withgrey-green leaf blades. The flowerheads starttightly packed like artists’ brushes, butdevelop into a conical open shape.

Key featuresYoung plant: There are red/pink strips atthe base of the shoots.

BiologyYorkshire-fog is usually found only in or nearfield margins. Established plants do not growover winter although the leaves may staygreen. New shoots are formed in the spring,but the leaves are short-lived. Reproduction isusually by seed, which can germinate rapidlyin a range of temperatures. Yorkshire-fog is aprolific seeder, with individual plants capableof producing up to a quarter of a millionseeds each season. As the seed is small andfine it can travel long distances carried bywind. However, seedling vigour is poor andyoung plants often fail to establish in densepasture.

ManagementIt is seldom a persistent problem within cropsand is reduced by spring cropping andploughing regimes, but is encouraged by grassbreaks.


WEED LIST BY EPPO CODE212

EPPO Code Scientific Name Common Name Weed Type ID

AETCY Aethusa cynapium Fool’s parsley Broadleaved

AGRRE Elytrigia repens Common couch Grass

AGRST Agrostis stolonifera Creeping bent Grass

AGSGI Agrostis gigantea Black bent Grass

ALAPE Alliaria petiolata Garlic mustard Broadleaved

ALOMY Alopercurus myosuroides Black-grass Grass

ANGAR Angallis arvensis Scarlet pimpernel Broadleaved

ANRSY Anthriscus sylvestris Cow parsley Broadleaved

APESV Apera spica-venti Loose silky bent Grass

APHAR Aphanes arvensis Parsley-piert Broadleaved

ARREL Arrhenatherum elatius Onion Couch Grass

ATXPA Atriplex patula Common orache Broadleaved

AVEFA Avena fatua Wild-oat Grass

AVELU Avena sterilis Winter wild-oat Grass

AVESA Avena sativa Oat Grass

BEAVX Beta vulgaris Sugar beet Broadleaved

BELPE Bellis perennis Daisy Broadleaved

BRANN Brassica napus ssp oleifera Oilseed rape Broadleaved

BROCO Bromus commutatus Meadow brome Grass

BRODI Anisantha diandra Great brome Grass

BROMO Bromus hordeaceus Soft brome Grass

BROSE Bromus secalinus Rye brome Grass

BROST Anisantha sterilis Barren brome Grass

BRSNI Brassica nigra Black mustard Broadleaved

Weed List by EPPO Code

WEED LIST BY EPPO CODE


CAPBP Capsella bursa-pastoris Shepherd’s-purse Broadleaved

CENCY Centaurea cyanus Cornflower Broadleaved

CENNI Centaurea nigra Knapweed Broadleaved

CERFO Cerastium fontanum Common mouse-ear Broadleaved

CHEAL Chenopodium album Fat hen Broadleaved

CIRAR Cirsium arvense Creeping thistle Broadleaved

CIRVU Cirsium vulgare Spear thistle Broadleaved

COIMA Conium maculatum Hemlock Broadleaved

CONAR Convolvulus arvensis Field bindweed Broadleaved

CYXCR Cynosurus cristatus Crested Dog’s-tail Grass

DACGL Dactylis glomerata Cock’s-foot Grass

DAUCA Daucus carota Wild carrot Broadleaved

EQUAR Equisetum arvense Field horsetail Broadleaved

ERICA Conyza canadensis Canadian fleabane Broadleaved

FERSU Festuca rubra Red fescue Grass

FUMOF Fumaria officinalis Common fumitory Broadleaved

GAETE Galeopsis tetrahit Common hemp-nettle Broadleaved

GALAP Galium aparine Cleavers Broadleaved

GERDI Geranium dissectum Cut-leaved crane’s-bill Broadleaved

GERMO Geranium molle Dove-s-foot crane’s-bill Broadleaved

HELAN Helianthus annuus Sunflower Broadleaved

HOLLA Holcus lanatus Yorkshire-fog Grass

HORVX Hordeum vulgare Barley Grass

KICEL Kickxia elatine Sharp-leaved fluellen Broadleaved

KICSP Kickxia spuria Round-leaved fluellen Broadleaved

213

WEED LIST BY EPPO CODE214


LAMAM Lamium amplexicaule Henbit dead-nettle Broadleaved

LAMPU Lamium purpureum Red dead-nettle Broadleaved

LAPCO Lapsana communis Nipplewort Broadleaved

LEGHY Legousia hybrida Venus’s-looking-glass Broadleaved

LIUUT Linum usitatissimum Linseed Broadleaved

LOLMU Lolium multiflorum Italian rye-grass Grass

LOLPE Lolium perenne Perennial rye-grass Grass

MATCH Matricaria recutita Scented mayweed Broadleaved

MATIN Tripleurospermum inodorum Scentless mayweed Broadleaved

MATMT Matricaria disoides Pineappleweed Broadleaved

MELAL Silene latifolia White campion Broadleaved

MYOAR Myosotis arvensis Field forget-me-not Broadleaved

PAPDU Papaver dubium Long-headed poppy Broadleaved

PAPRH Papaver rhoeas Common poppy Broadleaved

PHAPA Phalaris paradoxa Awned canary-grass Grass

PHLPR Phleum pratense Timothy Grass

PISSA Pisum sativum Pea Broadleaved

POAAN Poa annua Annual meadow-grass Grass

POATR Poa trivialis Rough-stalked meadow-grass Grass

POLAV Polygonum aviculare Knot-grass Broadleaved

POLCO Fallopia convolvulus Black-bindweed Broadleaved

POLLA Persicaria lapathifolia Pale persicaria Broadleaved

POLPE Persicaria maculosa Redshank Broadleaved

RAPRA Raphanus raphanistrum Wild radish Broadleaved

RUMCR Rumex crispus Curled dock Broadleaved

215WEED LIST BY EPPO CODE


RUMOB Rumex obtusifolius Broad-leaved dock Broadleaved

SCAPV Scandix pecten-veneris Shepherd’s-needle Broadleaved

SENJA Senecio jacobaea Ragwort Broadleaved

SENVU Senecio vulgaris Groundsel Broadleaved

SINAR Sinapis arvensis Charlock Broadleaved

SOLNI Solanum nigrum Black nightshade Broadleaved

SOLTU Solanum tuberosum Potato Broadleaved

SONAR Sonchus arvensis Perennial sow-thistle Broadleaved

SONAS Sonchus asper Prickly sow-thistle Broadleaved

SONOL Sonchus oleraceus Smooth sow-thistle Broadleaved

SPRAR Spergula arvensis Corn spurrey Broadleaved

SSYOF Sisymbrium officinale Hedge mustard Broadleaved

STEME Stellaria media Common chickweed Broadleaved

TAROF Taraxacum agg. Dandelion Broadleaved

TORAV Torilis arvensis Spreading hedge-parsley Broadleaved

TRZAX Triticum aestivum Wheat Grass

URTDI Urtica dioica Common nettle Broadleaved

URTUR Urtica urens Small nettle Broadleaved

VERAG Veronica agrestis Grield field-speedwell Broadleaved

VERAR Veronica arvensis Wall speedwell Broadleaved

VERHE Veronica hederifolia Ivy-leaved speedwell Broadleaved

VERPE Veronica persica Common field-speedwell Broadleaved

VICFX Vicia faba Field bean Broadleaved

VICSA Vicia sativa Common vetch Broadleaved

VIOAR Viola arvensis Field pansy Broadleaved

VIOTR Viola tricolor Wild pansy Broadleaved

GLOSSARY216

acidic(of soils) with a pH value of <6.5

alkaline(of soils) with a pH value of >7

ALS herbicidesherbicides containingsulfonylureas

annuala plant in which the whole life cyclefrom germination to seed dispersaland death occurs in one year

auriclein grasses, a hook-like projectionthat wraps around the stem, atthe end of the leaf sheath wherethe leaf blade meets the sheath

awnin some grass species, a bristle-likeprojection at the back or tip of aglume or lemma

axilthe place where a leaf stalk or leafblade meets the stem

basal rosettea cluster of leaves at the base ofthe flowering stem

beaka long thin extension of the tip ofa pod

biodiversitythe range of species found in aspecific area

bienniala plant which lives for two years,usually germinating in the firstyear and then flowering andproducing seed in the second year,before dying

biotypea group of individuals within aspecies that are genetically distinct

bladethe part of a leaf above the sheath�The blade is often flat, but canbe bristle-like.

boltera plant that flowers earlier thanothers around it

bracta modified leaf that is found in aflower or flowerhead � It may beone of a group of bractssurrounding the stem thatsupports a flowerhead, or it mayform part of a conspicuouscoloured structure surrounding aninsignificant flower in a leaf axil.

bracteolea small bract

Glossary

GLOSSARY

breaka period between two similarcrops when a different crop or nocrop is grown

break cropa crop grown between two relatedcrops, e.g. oilseed rape grownbetween two cereal crops

bristlea stiff hair, or very finestraight awn

broad-leaved(of plants) having leaves that arewider than they are long �Broad-leaved weeds are contrasted withgrass weeds.

bulbousswelling at the base of the stem,resembling a bulb

canopythe parts of a plant, especially theleaves, that receive light from thesun and shade the ground beneath

clasp(of a usually stalkless leaf) towrap around a stem

clonal colony or clonal patcha group of plants that aregenetically identical and differentfrom others growing around them

compact1. (of plants) having a neatgrowth habit

2. (of flowerheads) having theindividual flowers tightly packedtogether

compacted(of soil) compressed by thepassage of vehicles

competitivenessthe ability of a plant to growsuccessfully in relation to otherplants around it �Competitionbetween weeds and crop plantscan lead to yield reductions.

compositea plant that has flat flowerscomposed of florets arrangedaround a central structure, forexample a daisy, dandelion orsunflower �Composites aredicotyledons.

cotyledona green structure resembling a leafthat appears as a seed germinates,before the true leaves appear �Monocotyledons are plants suchas grasses that have a single firstseed leaf while the first leaves ofdicotyledons are in pairs.In broad-leaved plants, thecotyledons are usually a differentshape from the first true leaves.

217

GLOSSARY218

cross-fertilefertilised by receiving pollen fromanother plant. See also self-fertile

dicotyledona plant whose seed produces a pairof seed leaves as it germinates.See also monocotyledon

distribution1. the geographical area through-out which a plant usually grows

2. the way in which the seeds of aplant are spread

dormancythe period during which a seed orbud is not actively developing�Some seeds can develop a furtherperiod of dormancy (secondarydormancy) as a result oftemperature changes orcultivation practices.

downycovered with small soft hairs

emergencethe germination of a seed, whenthe cotyledons appear above theground

exploitto spread into or colonise an area

extendto grow longer

floreta small flower that forms part ofa flowerhead

flowerheada group of small flowers on asingle main stem

‘fop’ and ‘dim’ herbicidesherbicides containing chemicalssuch as diclofop or cycloxydim

fruitthe part of a mature flower thatcarries or encloses the seeds�Fruits may be dry seedheads, asin poppy, or fleshy, as instrawberries.

glanda group of cells that secretes asticky substance �Glands arefound in the sticky hair tips incut-leaved crane’s-bill, or in theswollen or fleshy bracts aroundflower clusters in spurges.

glandularhaving cells that secrete asticky substance

graminicidea herbicide used for killing grassspecies

grass breakSee break

219GLOSSARY

grass leySee ley

grass swardSee sward

groundkeepera plant that grows from a storageorgan such as a potato tuber or asugar beet accidently left in theground after harvest

habitthe characteristic way of growingof a specific type of plant

habitatthe type of environment in whicha specific plant grows

HBN herbicidesherbicides containing the chemicalhydroxybenzonitrile, such asioxynil or bromoxynil

herbicidea chemical used to kill plants,especially to control weeds�Selective herbicides, for examplebroad-leaved weed herbicides, areused to target specific types ofplants, while non-selectiveherbicides will kill all plantswhich are sprayed with them;contact herbicides have an effectonly on the plant tissue that theyare applied to, while systemic andhormone herbicides work bymoving through the plant tissues;

foliar acting herbicides are appliedto growing plants; residualherbicides are applied to an areaof ground and weeds are killed byuptake from soil.

hypocotylthe stem supporting a cotyledonor pair of cotyledons

infestationthe uncontrolled spread of weedsin an area

lateralgrowing at the side, or situated atthe side

leach(of nutrients, chemicals etc.) to bewashed out of the soil by rain orby irrigation

leafletan individual part of a leaf thatis divided

lemmain grass flowers, the lower of thetwo parts of a floret �The upperpart is the palea.

leyan area of grass sown as part of asystem of crop rotation

GLOSSARY220

ligulean extension of the leaf sheath,where it joins the leaf-blade�Ligules are one of the mostimportant identification featuresof a non-flowering grass species.

lipa projection on the lower part ofa tubular flower such as pea orred dead-nettle

lobea rounded division of a structure,e.g. a section of a divided leaf thatis not cut as far as the middle, orpart of a fruit

longevitySee seed longevity

mealyappearing to be spotted with orcovered in white powder

micro-speciesa group of plants that differs in itscharacteristics from other groupsand reproduces asexually

monocotyledona plant whose seed produces onlyone seed leaf as it germinates. Seealso dicotyledon

neutral(of soils) neither acidic nor alkaline,with a pH value close to 7

nodea slight swelling on a stem or axisfrom which a leaf or bract grows

oblongused to describe a flowerhead, leafor cotyledon that is longer than itis wide with parallel sides

openused to describe a plant or aflowerhead in which theindividual branches or flowers arenot tightly packed together

perenniala plant that lives for more thantwo years, flowering each year

persistentremaining or growing forseveral years

petalone of the often coloured parts ofa flower, surrounding the maleand female reproductive organs

pollinationthe process of transfering pollenfrom anther to stigma in a flower�This may occur within theflowers of a single plant (selfpollination) or between plants(cross pollination).

post-emergencethe period after the cotyledonshave appeared

221GLOSSARY

predationthe eating of seeds that have fallento the ground by small mammals,birds, etc.

prostrategrowing flat along the ground

regenerateto regrow

rhizomean underground stem that iscovered with scale-like leaves andcan root at the nodes �Rhizomesusually grow horizontally andmay store starch.

rogueingthe removal of plants, usually byhand, that are different from therequired standard of the rest ofthe crop

rosettea circular arrangement of leaves,all at one height, usually at thebase of the plant on the ground

rotationa system of cultivation in whichcrops that have different nutrientrequirements or are affected bydifferent diseases are either grownone after the other or areinterspersed with periods when nocrop is grown

row cropa crop that is planted in separatedrows, for example onion, lettuceor maize

secondary dormancySee dormancy

seed bankthe quantity of seed remaining inthe soil that is able to germinate

seed longevitythe length of time for which seedremains able to germinate

seed rainthe quantity of seed shed froma plant

seed setthe production of seeds

self-fertile(of a plant) able to be fertilisedwith its own pollen. See alsocross-fertile

sepalthe outer, usually green, leavessurrounding a flower

set seedto produce seeds

sheaththe lower part of a leafsurrounding the leaf stem

GLOSSARY222

shed1. to release seed

2. to lose leaves

solitary(of a grass plant) having a singlestem, rather than a group of stems

speciesa group of plants thatcan interbreed and havefertile offspring

spikean unbranched stalk ofindividual flowers, or groups offlowers (spikelets)

spikeletin grasses, a group of flowers,generally made up of two drybracts (glumes) and one ormore flowers

stale seedbedthe technique of allowing weed orcrop volunteer seeds to germinateso they can be removed beforedrilling. See also stubblecultivation

stamena single male part of a flower,consisting of an anther containingpollen and its stalk (filament)

stolona stem that grows along theground and produces roots andshoots at the nodes

stout(of plants) strong or robust

strap-shapedused to describe a leaf or petalthat has parallel sides but is verymuch longer than it is wide

stubble cultivationshallow cultivations after harvestto create favourable conditionsfor the germination of the seeds ofweeds and crop volunteers whichcan then be removed before or atplanting. See also stale seedbed

swardan area of grassland

taproota thick main root growingdownwards into the soil, withmuch smaller roots branching off it

tendrila thin clasping structure,developed from a stem, leaf orleaf stalk, that allows a plantto climb

223GLOSSARY

tiller1. a stem of a cereal or othergrass plant

2. to produce multiple stems

tilleringthe stage at which a cereal orother grass plant producesmultiple stems

toothed(of a leaf) having indentationsalong the edges

true leavesthe first leaves that are formedafter the cotyledon leaves haveappeared from the seed

tubera swollen part of a root orunderground stem, which is usedto store food for a plant and fromwhich new plants may grow

tufta group of several stems of a grassplant, which may be closely orloosely clumped together

tussocka dense raised clump of grass

umbellifera plant with a flat-toppedflowerhead (umbel) in which allthe main flower stalks join at acentral point, like the spokes ofan umbrella

unwinged(of a stem) having no outgrowthalong its length

vegetativeused to describe reproductionfrom plant parts such as tubersor rhizomes

veined(of a leaf or leaflet) havingthickened and prominent vesselsthat transport food and water

vigourthe rate at which seeds germinateand seedlings grow

vigorousgrowing strongly

volunteera plant that has not beendeliberately sown or planted

whorla set of three or more leavesgrowing from the same stem nodeand arranged in a circle

wingan outgrowth on a stem orseed case

REFERENCE MATERIAL AND FURTHER READING224

Further information

AHDB Cereals & Oilseeds Publications

Available at cereals.ahdb.org.uk/publications

G61: Managing weeds in arable rotations - a guide (2014)

G65: Oilseed rape guide (2015)

AHDB-IS03: Minimising the risk of glyphosate resistance (2015)

IS31: Identification and control of brome grass (2014)

IS30: Black-grass: solutions to the problem (2014)

IS17: Weed control in conventional and organic oats (2012)

IS09: Oilseed rape herbicides and water protection (2009)

IS06: Control of ALS-resistant chickweed and poppy incereals (2009)

BASF:

www.agriCentre.basf.co.uk

Others:

www.pesticides.gov.uk

DisclaimerWhile the Agriculture and Horticulture Development Board andBASF plc, Crop Protection seek to ensure that the informationcontained within this document is accurate at the time ofprinting, no warranty is given in respect thereof and, to themaximum extent permitted by law, the Agriculture andHorticulture Development Board and BASF plc, CropProtection accept no liability for loss, damage or injuryhowsoever caused (including that caused by negligence) orsuffered directly or indirectly in relation to information andopinions contained in or omitted from this document.

Reference herein to trade names and proprietary productswithout stating that they are protected does not imply that theymay be regarded as unprotected and thus free for general use.No endorsement of named products is intended, nor is anycriticism implied of other alternative, but unnamed products.

Reproduction of materialNo part of this publication may be reproduced, stored in orintroduced into a retrieval system, or transmitted in any form,or by any means (electronic, mechanical, photocopying,recording or otherwise), without the prior permission of thepublishers. Requests for permission should be directed toAHDB Cereals & Oilseeds and/or BASF plc, Crop Protection.

AHDB Cereals & Oilseeds is a division of the Agriculture andHorticulture Development Board (AHDB).

Date post:	31-Jul-2020
Category:	Documents
Upload:	others
View:	0 times
Download:	0 times

The encyclopaedia of arable Weeds Publication Docs/… · The weeds are ordered alphabetically by...

Documents