Problem Weeds of Turfgrasses
Tim R. Murphy
Crop and Soil Sciences
The University of Georgia
Why control weeds?
• Reduce crop yields and quality• Lower aesthetic appeal and property value• Some are allergens or poisonous• Disrupt native ecosystems• Harbor insects and diseases• Interfere with right-of-way safety and
transmissions
Weed Management Strategy
• Identify weed, life cycle, habitat
• Institute Control Procedures– Preventive
– Mechanical
– Biological
– Cultural
– Chemical
Virginia buttonweed
Virginia buttonweed (Diodia virginiana)
• Warm-season perennial broadleaf
• Reproduction– creeping stems
– creeping roots
– above and below ground seed production
Virginia buttonweed
• Seed germination
- optimum at 85 to 95 F.
- no germination < 70 F.
- optimum depth 1.0 to 1.5 inches
• Shoot emergence
- root fragments 0.25 inch long can
produce shoots from 8 inch soil depth
Virginia buttonweed - Control
• 2,4-D + 2,4-DP Good• 2,4-D + dicamba Good• 2,4-D+MCPP+dicamba Good• Research at MSU show formulations high in
2,4-D concentration provide better control (ex. Trimec Classic, Escalade)
• Spray regrowth when noted (21 to 35 days)
Virginia buttonweed - Control
• Ronstar - seed only
• Princep - seed only
• Confront, Manor - fair control (variable)
• Monument, Katana – good control (variable)
• Glyphosate - the last resort!
Sedge Herbicides - Turfgrasses
• Basagran T/O - yellow, annual sedges• Manage, SedgeHammer - yellow, purple, annual
sedges• Monument - yellow, purple, annual sedges• Katana - yellow, purple, annual sedges• MSMA/DSMA - yellow, purple, annual sedges• Image - yellow, purple, annual sedges• Certainty – yellow, purple, annual sedges• Pennant - yellow, annual sedges
Green (perennial) kyllinga
Kyllinga spp. (Kyllinga spp.)
• Sedge family
• Annuals and perennials
• Reproduce by seed and rhizomes
• No tuber formation
• Thrive in wet soils
• Increasing in severity
• Lack of MSMA use??
Kyllinga spp. - Control
• Image• Image + MSMA• Manage, SedgeHammer• Katana• Monument• Certainty• MSMA/DSMA
• Repeat applications will be needed
Sedge control ratings.
HerbicideAnnual Sedge
Purple Nutsedge
YellowNutsedge
Annual Kyllinga
Green Kyllinga
Pennant G F G F-G P
Certainty G G-E G-E G G-E
Basagran T/O G P G F-G F-G
Image G F-G P-F G G
Sedgehammer G G G G F-G
MSMA/DSMA G P-F F G G
Image+MSMA G G-E G G G
Monument ?? G-E G G G-E
Violet spp. (perennial)
Violets spp. (Viola spp.)
• Annuals and perennials• Shade or full sun• Reproduce by seed (rhizomes)• 2- and 3-way products - P to F• 2 appl. Confront, 3 to 6 wks apart• 2 appl. Chaser, Turflon II Amine. 4 wks apart• Katana, Manor, Blade
Wild garlic
Wild Garlic/Onion (Allium vineale and canadense)
• Cool-season perennial,reproduces by seed, aerial bulbils and underground bulbs and bulblets
• 2,4-D and other phenoxy products, 2 appl. 6 wks apart, 2 to 3 years
• Image - apply after dormancy, mow 1 to 2 wks after application
• Manor, Blade
Doveweed
Doveweed (Murdannia nudiflora)
• Summer annual, reproduces by seed
• fleshy stems, root at nodes
• 3 appl. MSMA + 2,4-D
• 2 appl. MSMA + Sencor
• Atrazine, 2 applications, 3 weeks apart
• 2 appl. Trimec Southern (14 d intervals)
Doveweed
• Ineffective Herbicides
- Basagran T/O
- Confront
- Vanquish
- Manor, Blade
Spreading dayflower
Spreading Dayflower (Commelina diffusa)
• Summer annual
• Reproduces by seed and stem fragments
• MSMA + Sencor
• Basagran T/O, Prompt
• MSMA
• Turflon II Amine (2,4-D + triclopyr)
Annual blue-eyed grass
Annual Blueeyed-grass(Sisyrinchium spp.)
• Annuals and perennials, Member of Iris family• Reproduce by seed• Thrives in compacted soils, some species like
moist soils• TranXit• Triazines in late fall• 2 appl. MSMA + Sencor, 14 d interval
Chamberbitter, niruri, gripeweed
Chamberbitter - Phyllanthus niruri
• Euphorbiaceae (spurge family)• niruri, gripeweed, leafflower• summer annual, reproduces by seed• alternate leaves, numerous leaflets• inconspicuous flowers• stalkless green, round fruit• no milky juice
Longstalked Phyllanthus
Longstalked Phyllanthus (Phyllanthus tenellus)
• Euphorbiaceae (spurge family)
• summer annual, reproduces by seed
• alternate leaves, numerous leaflets
• inconspicuous flowers
• stalked green, round fruit
• no milky juice
Chamberbitter & Longstalked Phyllanthus Control
• atrazine, simazine, 2 appl., 3 wks apart
• Ronstar - Pre (no home lawns)
• Gallery - Pre
• MSMA, 2 to 3 appl., 7 days apart ???
• 2,4-D+MCPP+dicamba ????
• Manor, Blade????
Prostrate spurge - summer annual
Postemergence: Manor, Blade, Sencor, Trimec, Monument
Preemergence: Simazine, atrazine, Gallery
summer annual
fireweed
Postemergence : 2- and 3-way growth regulator herbicides, Manor, Blade.
Preemergence products are not very effective or provide only short term control.
American burnweed (fireweed)
Pennywort or dollarweed
perennial
•Atrazine or simazine applied twice, 30 days apart.
•Prompt, Image, Manor, Blade.
•2 or 3-way broadleaf mixtures applied 7 days apart are also effective in tolerant turfgrasses.
Dichondra, rhizomatous perennial
Controlled by repeat applications of atrazine, 30 days apart.
2 and 3-way growth regulator herbicides. Confront is a little better than Trimec related compounds.
*Monument
Lawn burweed (spurweed)
Lawn Burweed - Soliva pterosperma
• Compositae (aster family)
• spurweed, sandbur
• winter annual, reproduces by seed
• opposite leaves
• fruits with sharp spines
Lawn Burweed Control
• atrazine, simazine - Pre or Post
• Gallery - Pre, early fall
• 2,4-D+MCPP+dicamba, repeat applications may be necessary
• Manor, Blade
• Katana
Florida betony
Florida Betony - Stachys floridana
• Labitae (mint family)
• “Rattlesnake weed”
• perennial
• reproduces primarily by tubers
• opposite, serrated leaves
• occurs in turf and ornamentals
Florida Betony Control
• atrazine - F-G
• 2,4-D - G
• 2,4-D+MCPP+dicamba - G
• Roundup, Finale
• Manor, Blade
Annual bluegrass – Poa annua
• Winter annual, but perennial biotypes also found on bentgrass greens
• Germinates late summer-fall at soil temperatures around 70 F.
• Second germination flush in mid- to late-winter
Continuous annual bluegrass seedgermination occurred from mid-Nov.through early January in Knoxville, TN.
Callahan and McDonald, 1992
Annual bluegrass control
Preemergence Control• Barricade, Pendulum• Surflan, Dimension• Balan, Ronstar• Kerb• Atrazine, Simazine
annual bluegrass
Boat shaped leaf tip
Non-Overseeded Bermudagrass
• Triazines – standard, but resistance increasing– Kerb – works, costly, lateral run-off
– Pre’s – work, but DNA resistance is here
– Glyphosate – works, partial dormancy
– Diquat – ineffective
• Revolver, TranXit, Monument, Certainty
Overseeded Bermudagrass
• Options for annual bluegrass• Kerb - 60 to 90 days (or charcoal)
– Dimension – 6 to 8 wks– Barricade – 8 to 10 wks (supplemental label)– Balan – low rate, 6 weeks– Rubigan – cost limits use to greens– Prograss – greenup issue – TranXit and Revolver – 2 weeks before seeding
Poa Control with Kerb
• Excellent for annual bluegrass
• Will move with water and damage cool-season grasses
Kerb movement onto bentgrass
Annual Bluegrass Control
Bentgrass Greens• paclobutrazol (Trimmit) at 0.25 lb/ac in the fall
followed by 2 to 3 applications in the spring.
• Pre’s tend to select for the perennial type Poa annua
• Roundup is effective• Monument, Revolver, Katana are effective• Kerb and Illoxan provides some control• Reward and Finale ineffective• Manor, Blade partial control
Italian Ryegrass
Italian Ryegrass Control
Herbicide Rate/A % Ryegrass Control
Roundup 2 qt 93
Finale 2 qt 43
Reward 2 qt 10
Illoxan 1.25 lb 47
Manor 1 oz 40
Overseeding
Clumpy perennial ryegrass
Monument, Revolver,
Katana
cool-season perennial
Tall Fescue
• Roundup (risky)
• Kerb during winter months
• Corsair, Monument, Revolver, Certainty, Katana
• Repeat applications of MSMA
• Usually 3 to 4 treatments required on a 5 to 7 day schedule
Dallisgrass
Dallisgrass – New Option
• Apply MSMA at normal rate
• Follow 2 weeks later with spot treatment of Revolver at 1.0 fl. oz/gallon
• Follow 7 to 10 days later with MSMA at normal rate
Roundup Rate and Bermudagrass Control
58
0
75
0
80
001020304050607080
% C
on
tro
l
2 qts 5 qts 10 qts
Roundup Rate/Acre
53 DAT 116 DAT
Bermuda Control with Roundup – 1 yr.
65
99
56
0102030405060708090
100
% C
on
trol
- 1 Y
R
4qt/2X 2qt/3X 2qt/2X
Rate Qt/Acre / No. of Apps.
Bermuda Suppression in Zoysiagrass
• Acclaim Extra – 20.0 fl. ozs./acre– Apply every 4 weeks during growing season
• Fusilade II– 3.0 to 4.0 fl. ozs./acre – Apply every 4 weeks during growing season
• Tank-mix with Turflon Ester at 1.0 qt./acre will improve control
Bermuda Suppression in Tall Fescue
• Apply 4 to 5 applications per year of Acclaim Extra at 20.0 fl. ozs./acre. Add Turflon Ester at 1.0 qt./acre to improve control. Apply every 4 weeks.
• Apply 2 applications (spring + fall) of Fusilade II at 5 to 6 fl. ozs./acre per year for 2 years
Bermuda Suppression in Centipedegrass
• Apply 2 applications (spring + 3 to 4 wks) of Vantage at 2.25 pts./acre per year for 2 years
• Apply 2 applications (spring + 3 to 4 wks) of Envoy at 34 fl. ozs./acre per year for 2 years (sod farm label)
Bermuda Suppression in St. Augustinegrass
• Prograss + Atrazine (2.0 gals. + 2.0 qts./acre)• 2 to 3 applications
– 1st – 2 to 3 wks after spring growth resumes– 2nd – 30 days later– 3rd - 30 days later if regrowth occurs
• Temp. injury and stunting to St. Aug. will occur• Avoid spray overlap or injury will increase
rhizome
seedhead
Bahiagrass
Repeat MSMA
Manor, Blade
rhizomes
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Turfgrass Web Page
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