Issue Number: 13 Date: 08/08/2014 PestFax PestFax is a weekly informative and interactive reporting service, providing risk alerts, current information and advice on pests and diseases threatening crops and pastures throughout the grain belt of Western Australia (WA). PestFax is supported by the Grains Research and Development Corporation (GRDC) and promotes national pest management information and Integrated Pest Management (IPM) principals. Newsletter of the Department of Agriculture and Food, Western Australia (DAFWA) Contents Root lesion nematodes Rhizoctonia Canola sclerotinia Barley leaf rust Native budworm moths Yellow spot on wheat Aphids commence to appear Barley yellow dwarf virus Anthracnose in lupins Pasture day moth caterpillars To view a map of pest and disease reports, see PestFax Map and PestFax newsletters for back copies of PestFax. If you have recently observed or heard news of insect or disease pests in crops and pastures contact [email protected]or use the online ‘make an on-line report ’ link.
Transcript
Issue Number: 13Date: 08/08/2014
PestFaxPestFax is a weekly informative and interactive reporting service, providing risk alerts, current information and advice on pests and diseases threatening crops and
pastures throughout the grain belt of Western Australia (WA). PestFax is supported by the Grains Research and Development Corporation (GRDC) and promotes national pest management information and Integrated Pest Management (IPM) principals.
Newsletter of the Department of Agriculture and Food, Western Australia (DAFWA) ContentsRoot lesion nematodesRhizoctoniaCanola sclerotiniaBarley leaf rustNative budworm mothsYellow spot on wheatAphids commence to appearBarley yellow dwarf virusAnthracnose in lupinsPasture day moth caterpillars
To view a map of pest and disease reports, see PestFax Map and PestFax newsletters for back copies of PestFax. If you have recently observed or heard news of insect or disease pests in crops and pastures contact [email protected] or use the online ‘make an on-line report’ link.
Root lesion nematodes Growers are urged to investigate uneven crops to check if plant parasitic nematodes are present. DAFWA nematologist Sarah Collins recently visited the Moora area where a number of wheat and barley crops are being damaged by root lesion nematodes (RLN) (Pratylenchus) and burrowing (Radopholus) nematodes. Samples collected from one of these sites was diagnosed by AGWEST Plant Laboratories as the RLN species Pratylenchus penetrans. This was unexpected as this species is more often associated with cropping in the cooler growing areas. The ‘burrowing nematode’ detected in a nearby barley crop is also interesting as crop damage has not been reported for this plant parasitic nematode for a number of years. Correct identification of nematodes is important because the choice of suitable break crops to mitigate future crop damage
is dependent on knowing which plant parasitic nematode species are present. Sarah speculates that consecutive seasons favourable to RLN and burrowing nematode and the increasing inclusion of canola to crop rotations may be contributing to the build-up of nematode numbers. The reports this year confirm survey work by the Focus Paddocks project, supported by GRDC, which has detected increasing levels of Root Lesion Nematode across the 184 paddocks surveyed since 2010.
Above ground symptoms of plants infected with root lesion and burrowing nematodes include stunting, poor growth, plants prone to early wilting and lower leaves turning yellow prematurely and dying back from the tips. Below ground symptoms often show reduced root systems with fewer lateral roots and root hairs compared to nearby healthy plants. Brown/dark coloured lesions along the roots may also be seen. For an overview of RLN symptoms in paddock visit the
webpage: How to diagnose Root Lesion Nematode. For assessment, carefully dig up samples of diseased plants from the edge of the patch (not the centre) as well as healthy plants that are not in
patches. For sampling information visit the webpage: How to take a plant sample. Suspected root disease or nematode problems in-crop can be confirmed by a chargeable laboratory analysis of soil and/or roots by AgWest Plant Labs. Send fresh samples of plants with intact roots in an undisturbed soil ball (not washed roots) using sampling guidelines available at the Department’s AGWEST Plant Labs. The cost is $308 per sample.
For further information and pictures of disease symptoms visit the webpage “Root disease under intensive cereal production systems”.
RhizoctoniaBrad Smoker (Synergy Consulting) reports finding patches of poorly grown Mace wheat in a paddock near Kulin. The paddock has been in continuous cereal rotations for the past seven years apart from a canola break crop in 2012. Interestingly small patches of crop several meters in diameter with stunted growth are in the same locations as where they were also seen last year (2013 also Mace wheat).
Growers and agronomists contacted by DAFWA northern agricultural region staff commented that patches of rhizoctonia bare patch disease has been seen in wheat crops in the Buntine and Wongan Hills areas. As expected the disease is showing up in paddocks with a high incidence of wheat in rotations and with low levels of nitrogen.
What to look for
Plant Pathologist Daniel Hüberli says that rhizoctonia bare patch is usually noticed by the appearance of severely stunted plants often in a circular patch with a distinct edge next to the surrounding healthy plants. Patches vary from a less than half a metre to several metres across. When plants are dug-up, carefully washed and examined the rhizoctonia infected plants will have shorter root systems than healthy plants and their root growth will end with dark spear tips where the roots have rotted through.
Control
Current management practices recommended to control the disease are for deep cultivation below the seed level (at least 10 cm below the seed) in combination with a registered fungicide seed dressing such as Evergol Prime™ or Vibrance™.
Wheat and barley collaborative trials in Western Australia and South Australia have shown that liquid banding with Unifiorm™, one of several fungicides tested, increased yields by up to 0.87 tonnes per hectare in a paddock with very high levels of rhizoctonia in the soil before sowing.
The APVMA has approved permits for large-scale trials this season by chemical companies and is considering an application for registration, which, if approved, could make the products available in 2015.
Although the fungicide work is a promising tool to assist control Daniel is warning that when available it will need to be used as part of an integrated disease management program. That is, used in conjunction with deep cultivation, rotation of break crops, seed dressings and ensuring adequate nutrient supply.
An accurate diagnosis of root diseases is essential in planning paddock crop rotation and establishment practices for next season. Current season crop samples can be submitted to Agwest Plant laboratories for diagnosis of the disease or diseases contributing to the observed symptoms. The PreDicta B DNA based soil testing service is another alternative available to identify soilborne pathogens that may be causing problems. The correct time for sampling for PreDicta B is normally prior to sowing time, however, samples can be sent for in-season confirmation of soilborne disease.
For further information and pictures of disease symptoms visit the webpage “Root disease under intensive cereal production systems” and the GRDC Fact Sheet: Management to minimise Rhizoctonia disease in cereals, DAFWA MyCrop Rhizoctonia information and Crop update papers: Integrated disease management options to control rhizoctonia bare-patch in cereals.
Canola sclerotiniaRick Horbury (Bayer Crop Science) reports that dry weather conditions for part of this week slowed the progression of sclerotinia stem infection on canola crops he has been inspecting in the West Midlands area. Most crops are at the 20-60% flowering growth stage, dependent on variety and location. Rick observed sclerotinia leaf lesions appearing (some about a week old) in the area between Badgingarra, Bolgart, Meckering and York. These lesions seem to correlate strongly with areas where the tiny mushroom sclerotinia fruiting bodies (apothecia) were previously found.
Ashton Gray (ConsultAg) reports that he could easily find sclerotinia apothecia this week within a barley crop that was sown into canola stubble near Darkan.
Plant Pathologist Ciara Beard has found lots of sclerotinia leaf lesions and the start of some stem infections in a DAFWA trial at Moonyanooka (E. Chapman). However a recent period of warm and dry conditions stalled the disease progression.
Canola Pathologist Ravjit Khangura reports finding sclerotinia leaf lesions in an opportunistic DAFWA trial near Moora this week. She says that although disease development halted during the period of dry weather, new sclerotinia mould infection has been found in some crop canopies where the leaf axis or the lowest leaves retained sufficient moisture. Recent rainfall (7/8/14) in some districts could be enough to re-commence infections. Spores released from high numbers of apothecia that are surviving on last year’s sclerotinia infected paddocks and are likely to initiate fresh infections in nearby canola crops where canopy moisture levels are conducive.
Ravjit says there are lots of reports of growers in high rainfall areas spraying their canola for sclerotinia control. Along with many agronomists Ravjit is advising growers to assess their risk before deciding to spray their crops. The key risk factors include paddocks having a history of sclerotinia in the past three years, current canola sown within 1 kilometre and downwind from last year’s paddock affected with sclerotinia and frequent rain events before and during flowering.
Fungicides are likely to provide economic benefit in moderate to high disease risk situations but low risk crops are unlikely to gain any economic return from fungicide application. Additionally growers need to consider yield potential and canola price. With the early sclerotinia spore release
this season it is likely that early fungicide application between 20-30% flowering will be more cost-effective in disease risk areas.
For more information on the sclerotinia lifecycle, disease symptoms and management strategies see last week’s PestFax 1 Aug 14 and the DAFWA webpage Managing sclerotinia stem rot in canola .
Barley leaf rustQuenten Knight (Precision Agronomics Australia) has seen more (PestFax 1 Aug 14) barley leaf rust at Mt Ridley, 75Km east of Esperance. The crop is Bass barley, just approaching flag leaf emergence on the main tiller, and the infection is at low levels. Crops will be sprayed with appropriate fungicide this week. No previous foliar fungicide has been applied this season, however it is interesting to note that Baudin crops on the same farm that were sprayed with Prosaro 3-4 weeks ago for powdery mildew are not showing any signs of barley leaf rust. For further information and images of barley leaf rust visit the webpage: Barley leaf rust.
Plant pathologist Kith Jayasena recommends that growers in Southern and South coastal agricultural areas keep a close watch on their barley crops for rust and other disease progression, especially powdery mildew which is also present in the region. He advised growers to be ready to spray infected crops with appropriate fungicides before disease levels become too advanced. Barley leaf rust has also been found in the South Stirling’s area this year see PestFax Map
Due to the new leaf rust pathotype being detected on the south coast, which affects varieties carrying the Rph3 resistance gene such as Bass, Plant pathologist Kith Jayasena suggests that leaf rust samples should be sent for pathotype testing. He encourages growers and agronomists to collect infected leaf samples and mail them in paper envelopes (do not use plastic wrapping or plastic lined packages) along with your details and collection information (location etc.) directly to the Australian Cereal Rust Survey, Plant Breeding Institute, Private Bag 4011, Narellan NSW 2567.
For further information visit the webpages: Managing barley leaf diseases in Western Australia and lists of registered foliar fungicides for cereals in WA 2014
Native budworm mothsResults from native budworm trappers this week indicates large flights of budworm moths have occurred this week in the south Doodlakine area with 234 moths caught and Eradu with 287 moths caught, both traps were positioned in lupin crops. Other smaller flights of moths were detected in traps at (numbers in brackets) Badgingarra (2), Cowcowing (6), Doodlakine (5), Kellerberrin (1), Kirwin (91), Maya (3), Mollerin (42) and Wyalkatchem (1).
Matt Willis (Elders) used an insect sweep net to check a canola crop south of Mollerin this week and found an average of 3.5 grubs (size 0-10mm) per 10 sweeps.
Native budworm moths arriving into flowering crops now maybe ready to lay eggs or may feed on flower nectar and mate before becoming fertile. Eggs laid by moths at this time of the year will take at least two weeks before they grow to a size of approximately 5 mm long and can be detected whilst netting crops. Early flowering susceptible crops such as field peas should be checked for budworm caterpillars using a sweepnet.
Native budworm moth flights are often variable and unpredictable but moths generally prefer to land in flowering crops in preference to nearby crops that are yet to flower. Field pea, faba bean, lentil and chickpea crops are very susceptible to budworm as their pods are attractive to all sizes of caterpillars. These crops need to be checked regularly after the commencement of flowering
with growers prepared to apply sprays if threshold levels of caterpillars are discovered. Serradella, lucerne, clover and annual medic seed crops will also be at risk of attack.
Lupin and canola pods are less attractive to native budworm caterpillars which do not commence to feed on these pods until closer to leaf drop and pod maturity. Decisions on spray application to these crops should be delayed until closer to maturity.
The moth numbers present an early warning of moth activity and distribution but unfortunately represent only very small areas and are as such no substitute for individual canola and pulse crops being checked by growers for caterpillars using a sweep net. The economic spray threshold levels will vary with crop type, grain price and control cost; these can be calculated for each grower’s particular situation using a simple formula outlined in the webpage: Management and economic thresholds for native budworm.
Yellow spot on wheatAshton Gray (ConsultAg) reports that a crop of Yitpi wheat near Quairading has high level so yellow spot infection. The crop is commencing flag leaf emergence and will be sprayed with fungicide.
Many wheat crops in the grain belt are showing signs of yellow spot infection, especially on susceptible varieties such as Yitpi. A consultant commented to DAFWA central agricultural area staff that some of the yellowing of lower canopy leaves is from nitrogen deficiency and cold stress and is not always disease related.
Where the incidence of the disease is of concern, farmers are applying fungicides (often in conjunction with nitrogen application) to restrict further development of the disease.
Help needed to stop the spotCaroline Moffat (Centre for Crop and Disease Management, Curtin University) requests that next time you notice yellow spot infection, please spare a minute to pick off a few infected leaves and mail them to the Curtin University yellow spot research team. Recovered fungal strains will be tested for toxin production and virulence, and used to help in the identification of more resistant varieties. Please visit the webpage Stop the spot to request reply paid sampling envelopes.
For further information visit the webpage: Managing yellow spot and septoria nodorum blotch in wheat
A list of registered fungicides to use as foliar sprays are available at the webpage: Registered foliar fungicides for cereals in Western Australia (WA)
Aphids commence to appearAshton Gray (ConsultAg) reports cereal aphids are commencing to build in numbers on a barley crop growing east of Quairading. The crop is in the late booting growth stage (Z45-49) with an average of 4 aphids per tiller currently being found. The crop will continued to be monitored.
A consultant reported to the DAFWA Central Agricultural Region staff that cereal aphids have commenced to build in numbers on a cereal crop near Brookton. He also saw winged cabbage aphids on a canola crop near Tammin. Another consultant reported to the DAFWA Northern Agricultural Region staff that low levels of aphids have also been seen in the Coorow area.
These reports of aphids are a good early warning for growers to be checking their crops. Aphids are present in most cereal and canola crops every year although in most years their numbers remain below economically damaging levels.
Barley yellow dwarf virusA consultant reported to DAFWA Central Agricultural Region staff that he found plants infected with barley yellow dwarf virus (BYDV) near Brookton this week. Colonies of aphids were also present on the crop.
Plant virologist Brenda Coutts says that BYDV symptoms can vary. In barley the symptoms are yellowing of the older leaves, starting with some striping from the tip of the leaf towards the base. Whereas in wheat varieties there can be yellowing or reddening of older leaves. This is particularly clear in the flag leaf. BYDV can often be distinguished from nutritional deficiencies by it's pattern of spread. After initial infection of a single plant, virus infected aphids may move from this to neighbouring plants and the infection spreads outwards in a circle. As well as circular patches of yellowing or reddening plants, virus spread is often found along the margins of crops. It is recommended where aphids can be seen in tillering crops in high BYDV risk areas, farmers should not delay their insecticide applications or the yield benefits from BYDV control will be minimal. The recommendation for high risk situations is a first spray of synthetic pyrethroid (SP) insecticide as soon as aphids are seen or 3 weeks after crop emergence, and a follow up spray 4 weeks after the first spray or 7 weeks after emergence of insecticide treated (Gaucho®) seed. It is too late to apply SP sprays (whether 1st or 2nd) to prevent BYDV transmission once crops have advanced to the early stem extension stage (GS 31) as BYDV has little significant economic impact if the infection occurs after this growth stage.
Cereal varieties also vary in their susceptibility to BYDV e.g. Hindmarsh barley is susceptible (S) and Buloke barley is moderately resistant to moderately susceptible (MR- MS) for further ratings see the 2014 DAFWA barley variety guide. From more information on BYDV visit the webpage: Managing barley yellow dwarf virus and cereal yellow dwarf virus in cereals.
Anthracnose in lupinsFollowing last week’s report of anthracnose disease in lupins, Chris Wilkins (Synergy Consulting) advises that lots of anthracnose infection is being seen in wild blue lupins in the Badgingarra area.
Plant Pathologist Geoff Thomas says that blue lupins are a common source of anthracnose inoculum. Where possible blue lupins should be destroyed to maintain a separation from susceptible cultivated lupin varieties. He advises growers to observe their lupin crops and to be aware of any incidence of anthracnose disease.
For further information see last week’s PestFax 1 Aug 14 and DAFWA webpage Lupin foliar diseases: diagnoses and management.
Pasture day moth caterpillarsAn agronomist reported to DAFWA Central Agricultural Region staff that pasture day moth caterpillars have continued to be found in some crops in the Merredin area and also a crop near Beacon which has damaging levels of caterpillars.
Also available:List of registered insecticides
A list of registered insecticides to control autumn/winter pests on canola, lupins and cereals is available on the PestFax webpage: Autumn Winter Insecticide Guide 2014
This book covers crop pests, beneficial insects, biological control, grain storage pests and biosecurity pest threats specific to WA. Copies are available from some DAFWA offices for a cost of $10.00 or by mail order by phoning the DAFWA South Perth office on +61 (0)8 9368 3710.
Free insect identification Having troubles identifying mites or other pests? For free identification, send your digital pictures (in focus) or live specimens (in a non-crushable plastic jar) to Peter Mangano or Svetlana Micic at the postal details below.
Svet Micic, DAFWA Albany 444 Albany Highway, Albany WA 6330Email: [email protected] Phone: +61 (0)8 98928591 or +61 (0)427 772 051
Peter Mangano, DAFWA South Perth3 Baron-Hay Court,South Perth WA 6151Email: [email protected] Phone: +61 (0)8 9368 3753 or +61 (0)404 819 534
Integrated Pest Management Guidelines for grains
AgTactics and AgMemo Other regional DAFWA news updates are available on DAFWA website .
Seasonal climate outlook Seasonal climate outlooks are available on DAFWA website .
AGWEST Plant Labs
Plant disease diagnostic services are located at the DAFWA South Perth office. For information on sending samples and charges contact +61 (0)8 9368 3721 or Fax +61 (0)8 9474 2658 or visit the
DAFWA website or the AgWest plant laboratories webpage.
