Issue Number: 04Date: 06/06/2014

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 National Invertebrate Pest Initiative (NIPI) a Grains Research and Development Corporation (GRDC) project that promotes national pest management information and Integrated Pest Management (IPM) principals.

Newsletter of the Department of Agriculture and Food, Western Australia

ContentsMites and lucerne fleaWheat leaf rust found in regrowth MaceBarley powdery mildew Other cereal leaf diseaseHard to kill weevilsCaterpillarsSlugsMiceFungal gnats

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: PestFax@agric.wa.gov.au or use the online “make an on-line report” link.

Mites and lucerne fleaEarth mites have continued to require control in unsprayed pastures and some late sown crop paddocks. Lucerne flea have also continued to be found in damaging numbers requiring control on some seedling paddocks with clay/loam soil types that are favoured by this pest.

Northern Agricultural Region (NAR) Department of Agriculture and Food Western Australian (DAFWA) staff received reports of lucerne flea in damaging numbers from agronomists at Northampton, Mingenew and Moora. Wayne Parker (DAFWA) also reports that a number of growers have needed to control damaging levels of lucerne flea on clay/loam soil types in Moora and Dalwallinu areas.

Alana Hartley (Landmark) reports that lucerne flea and redlegged earth mites have been causing damage to some later sown cereal crops in the Wongan Hills area.

Bill Crabtree (Crabtree Agricultural Consulting) reports that lucerne flea feeding damage to a seeding canola crop near Wongan Hills has retarded and delayed plant growth within affected patches of the crop associated with higher pest population and soil type. The canola is due to be sprayed with herbicide for grass control soon and the opportunity to tank mix insecticide for a one pass operation is desirable. However there is a concern that the chemical cocktail may have excessive uptake on the lucerne flea damaged leaf cuticle and result in some herbicide burn.

Sam Repacholi (Landmark) reports that redlegged earth mite numbers have decreased with recent warm weather in the Esperance region. Sam has also found high numbers of Balaustium mites along with low levels of bryobia mite attacking a canola crop near Gibson. As many as 5–10 balaustium mites per canola cotyledon can be seen in some patches of the crop. Typical leaf cupping and shrivelling damage caused by the balaustium mites is being compounded by dry soils and moisture stressed plants restricting plant growth.

Nathan Moyes (Moyes Agri Consulting) reports that he has found Balaustium mites on seedling canola (two mites per cotyledon) and barley seedlings (three mites per leaf) on crops growing in the Kojonup area. The Balaustium were wide spread over the paddock. Nathan has also seen lucerne flea causing damage to canola and barley seedling crops in Kojonup and southern cropping areas. These crops were sprayed to prevent further damage from occurring.

Nathan is also seeing wide spread hatching (possibly second generation) of redlegged earth mites from Bridgetown to Newdegate. Along with these mites he is also finding predatory pasture snout mites in paddocks. The snout mites are being found in canola paddocks that were seeded following pasture or barley rotations in the Kojonup to Beaufort area.

Predatory mitesThe pasture snout mite, bdellodes spp.(P111 Crop Insects: the Ute Guide WA), is an important biological control agent as it feeds on lucerne flea and earth mites as well as other commonly found non-pest springtails. The predatory pasture snout mites are present over most of the WA grainbelt where lucerne flea occurs and they provide a useful level of control in pastures. Another useful predatory mite, the spiny snout mite (Neomolgus capillatus), was introduced many years ago but unfortunately it has difficulty surviving cropping/grazing systems and its distribution is limited to localised areas.

For further information on earth mites and lucerne flea can be found in following links – GRDC snout mites, Diagnosing lucerne flea , Diagnosing redlegged earth mites and Diagnosing bryobia mite

Wheat leaf rust found in regrowth MacePlant pathologist Kith Jayasena reports seeing leaf rust on regrowth Mace in early May in the Borden area. Since Mace is currently the most popular widely grown variety in the region and with the new wheat leaf rust pathotype detected last season, Kith recommended that growers across the wheatbelt be vigilant about controlling volunteer Mace regrowth in paddocks not cropped this year as the season progresses.

DAFWA plant pathologists Geoff Thomas and Manisha Shankar have recently completed glasshouse trials to test the seedling and adult reaction of Mace and other varieties to the new wheat leaf rust pathotype. In these tests the response of Mace to this pathotype was moderately susceptible (MS) or worse at all growth stages. Similarly the varieties Wyalkatchem and Corack were moderately susceptible to susceptible. However the varieties Cobra and Carnamah were not adversely affected and appear to be moderately resistant or better.

While in most areas there were few volunteers present over summer and autumn, it remains important to regularly monitor crops for the presence of a range of diseases including leaf rust.

Early detection and awareness of new pathotype virulence against current resistant cereal varieties enables the grains industry to direct management and research to the most needed areas. Samples of any leaf rust detected should be mailed in paper envelopes; do not use plastic wrapping or plastic lined packages, to the Australian Cereal Rust Survey, Plant Breeding Institute, Private Bag 4011, Narellan NSW 2567, Ph (02) 93518800 for pathotype analysis. For further details see University of Sydney Plant Breeding Institute website.

Barley powdery mildewNathan Moyes (Moyes Agri Consulting) reports that he is starting to see powdery mildew disease appearing in barley crops around Kojonup and southern areas.

Dr Kith Jayasena (DAFWA pathologist) says that, in his spore traps at Tenterten, he is seeing barley powdery mildew conidia spores along with: canola blackleg asco spores and barley net blotch conidia. The spore traps are designed to capture and monitor samples of aerially dispersed fungal spores.

For further information on management of this disease see the: Management of barley powdery mildew in 2014 - fungicide resistance DAFWA webpage.

Other cereal leaf diseasesAlana Hartley (Landmark) reports finding early symptoms of yellow spot infection in a seedling Calingiri wheat crop near Wongan Hills. The paddock has a noodle wheat on noodle wheat crop rotation.

Alana also reports that net blotch infection is present in barley crops in the Wongan Hills area, with farmers choosing to apply fungicide to contain the disease in some paddocks.

For further information on yellow spot infection see the Managing yellow spot and septoria nodorum blotch in wheat DAFWA webpage.

For information on symptoms and management of net blotch, see the Managing net type net blotch and spot type net blotch in Western Australia webpage, which is available along with other disease management information including Registered foliar fungicides for cereals in Western Australia, publications on specific diseases, variety disease ratings, disease forecasts and instructions for submitting plant samples on the crop disease page on the DAFWA website.

Hard to kill weevilsRichard Quinlan (Planfarm Agronomy) reports that weevils have caused extensive damage to a canola seedling crop east of Dongara. The paddock was treated with high rates of insecticides post sowing pre-emergence which failed to reduce their populations below economically damaging levels. Large patches of the crop have been either bared off or have very low surviving plant densities as a result of the weevil chewing damage. The farmer is considering re-sowing substantial areas of his paddock. Richard noticed that the weevils did not look like the common vegetable weevil or desiantha weevil but were different. Samples have been collected and digital images sent to DAFWA entomologists.

The weevils appeared to be causing more damage on the areas of the paddock with heavier soils and were difficult to find during the day. Applying a control spray at night when the weevils are likely to be more active is being considered.

The same weevils were reported in the area during 2013 on a separate property but in the same vicinity, north east of Dongara. Samples of these weevils have remained unidentifiable to date by DAFWA entomologist Andras Szito and another Australian taxonomist. They are assumed to be an unknown species believed to be a native species localized in the area.

Other reports of hard to kill weevils in the Dandaragan area were reported in PestFax No.3, 30 May 14. These are also an unknown weevil species, but are not the same as the Dongara weevils.

Entomologist Svet Micic also commented that yet another unidentified weevil species was found causing damage to several canola crops in the South Stirlings during 2010 and 2013. This weevil was found in conjunction with other commonly known pest weevils. Early season sprays in the canola paddock in 2013 were not effective as there was abundant surface stubble and when sprays were applied it is unlikely that the weevils were actively moving above the stubble. The

weevils were found adjacent to native vegetation and were not troublesome again in the same paddock.

Sam Repacholi (Landmark) reports that a moisture stressed seedling canola crop near Grasspatch, has patches that are badly damaged by desiantha weevils. Typical crescent shaped chewing damage to the leaves of the seedling crop can be seen but the weevils have also chewed through some of the stems. Surprisingly the weevils were easily found adjacent to damaged seedlings in the middle of the day.

Weevil identificationRelative to common pest weevil species the unidentified Dongara weevils are similar in size to desiantha weevils, about 5 milllimetres (mm) long whilst vegetable (12mm) and small lucerne weevil (10mm) are larger. The Dongara weevils have a shiny black appearance, blunt nose and prominent bent antennae. The Dandaragan weevils are even smaller about 3mm long with a mottled dull grey colour.

Life historyWeevils generally have one generation per year. Most are flightless and complete their lifecycle within the same paddock or only travel short distances. Rainfall in autumn or early winter stimulates the adults to emerge from their over-summering sites (e.g. under stubbles and rocks etc.) where they have survived in a dormant state. In some years weeds provide an early food source for adult weevils. During the winter period they continue feeding, mating and laying eggs.

Larvae develop in the soil during winter/spring and before a period of pupation and emergence as adults. Weevil larvae mostly feed beneath ground on the root systems of plants; however some (e.g. vegetable weevil) feed above ground on plant leaves. Desiantha weevil larvae are known to feed on the root systems of cereal crops and in some years have cause economic damage to late sown crops. The unidentified Dongara weevils are also likely to develop on cereal roots, as some of the paddocks found with the pests have had cereal rotations for a number of years prior to canola being sown.

ControlIt is assumed that the hard to kill Dongara and Dandaragan weevils have a higher tolerance for chemicals that the other common pest species. It is also quite likely that they have some behavioral characteristics that enable them to shut down and ‘hide’ for periods of time, before again resuming feeding.

South Australian Entomologist Kym Perry commented on work conducted with control of the troublesome mandalotus weevils found in parts of Eastern Australia (not WA). His research shows that fipronil seed treatments provide some control of adults but did not protect seedlings against high weevil populations. Upper label rates of bifenthrin applied at sowing for redlegged earth mite provide 50-70% control of surface active adults. Bare earth treatments of alpha-cypermethrin or chlorpyrifos were not effective (0-20% control) in his trials.

Need your helpReaders are encouraged to send in any unusual looking weevils, especially those that might have survived recent insecticide sprays. Free identification and advice will be provided to those who send in samples. For where to send please see ‘free insect identification’ details below.

For further information on commonly occurring weevils see the following links – Diagnosing weevils in canola and Diagnosing desiantha weevil in cereals

CaterpillarsCutworm

David Stead (Anasazi Agronomy) reports finding small to medium sized cutworm caterpillars damaging a wheat crop north of Dowerin. The crop was sown into last season’s pasture and received separate alpha-cypermethrin (pre-plant) and chlorpyrifos (PSPE) sprays which failed to prevent the cutworm moth eggs and larvae developing.

Numbers of cutworm caterpillars are often underestimated as many of the species are concealed beneath the soil surface during the day and emerge to feed during the night. At least four species of cutworm are known to be pests in WA and only one of them is usually found feeding above ground during the day, the black cutworm (Agrotis ipsilon). The other species bogong moth, pink cutworm and herringbone cutworm all feed at night and can only be found during the day by digging down just below the surface or to about 3 centimetres deep, near freshly damaged plants.

Cutworms feed at or near ground level and are given their name because they often chew through leaves or stems giving a cut-off appearance. When disturbed most of the cutworm species curl up and remain still. Small cutworm caterpillars have small mouthparts and cause relatively minor damage which can sometimes be overlooked. However damage to crops and pastures will increase significantly as the caterpillars grow larger causing much more damage per grub.

Monitoring at night with a torch will aid in finding night feeding pests that are responsible for plant damage which would otherwise not be found during the day.

Pasture day moth caterpillarsAlana Hartley (Landmark) reports that pasture day moth caterpillars are causing damage to some canola and cereal crops in the in the Wongan Hills area.

Pasture day moth caterpillars rarely cause economic damage as they have a preference to feed on broadleaved weeds in pasture, such as erodium and capeweed. In some years however, there numbers have been high enough to cause economic crop damage to cereals, especially in situations where broad-leafed weeds have been removed by recent herbicide applications.

SlugsDavid Stead (Anasazi Agronomy) reports that slugs have caused extensive damage to at least five hectares (ha) of a seedling canola crop growing west of York. The crop was sown into barley stubble and was establishing well when last inspected (whilst spraying weeds) about two weeks ago. Now there are large patches of the crop that have been severely thinned or bared off by slug feeding damage. Most damage is occurring close to contour banks and bushland where it is assumed the slugs had been sheltering. The slugs have been difficult to find during the day but those found are a mottled brownish colour indicating they are most likely the reticulated slug (Deroceras sp.).

An agronomist from the Dalwallinu area reported to DAFWA northern agricultural area staff that slugs have caused patch damage to some crops in his area. The affected paddocks are on soils with high clay content which is usually favoured by slugs and aids in their survival over summer.

Nathan Moyes (Moyes Agri Consulting) reports that slug damage has occurred in canola crops in the Kojonup to Bridgetown area. Baiting has taken place in some paddocks but generally crops are out growing moderate damage levels. In some cases there has been more than one pest present in the paddock. In some cases slater damage has been mistaken for slug damage.

Plant Pathologist Ciara Beard reports that slugs have caused damage to patches of a canola crop near Walkaway. The affected paddock has a loam/clay soil and lots of wheat stubble residue which is helping to retain moisture and humidity. The grower is putting out slug pellets to minimise the damage and reduce slug breeding opportunity.

A farmer near Geraldton reported to Entomologist Svet Micic that for the first time in 10 years he is having slug damage to his canola crop. He is baiting to control the slugs and sending a sample to DAFWA for identification. Svet says that the black keeled slug which burrows under the soil surface are usually more damaging than the surface dwelling reticulated slug. Black keeled slugs are better able to survive hot dry conditions and can feed on germinating seed in furrows.

Visit the SARDI website to view information on snail (and slug) baiting, and for further information on snails refer to the GRDC Snail Management Fact Sheet and Identification and control of pest slugs and snails for broadacre crops in WA .

MiceSam Repacholi (Landmark) reports that a seedling canola crop near Salmon Gums has patchy damage from mice feeding. The damaged patches of crop are approximately 50 x 50 metres with numerous mouse holes in the middle. The mouse holes seem to be in greater numbers on the side of the paddock closest to pasture. The crops are currently under moisture stressed from lack of rain and poison baits are being applied to reduce the damaging mice.

David Stead (Anasazi Agronomy) reports that mice have also been found damaging a seedling canola crop growing near Hyden.

For more information please refer to the GRDC Mice Control Factsheet, Western Region .

Fungal gnatsDaniel Dempster (farmer/agronomist) reports that clusters of small (about 3mm long) dark coloured crawling insects are being seen at the base of on a canola crop growing north of Meckering. On closer inspection the winged mini-fly like insects were found rise up from the ground when disturbed. The crop was sown into a barley stubble and is in a low lying paddock on a blue clay soil type that is subject to waterlogging.

The description of the insects and the habitat where they are being found fits that of fungal gnats. There are many different species of fungal gnats but none are known to be damaging to grain crops. The larval stage of the flies (maggots) usually feed on fungal material near the ground and occasionally on tender living plant tissue. They will be more prevalent in moist damp areas of the paddock. The adult flies mostly gather together in colonies and can be seen flying close to the ground or actively running over the soil surface.

Also available:Crop insects: the ute guide This book covers crop pests, beneficial insects, biological control, grain storage pests and biosecurity pest threats specific to WA. Copies are available from some Departmental 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? Send in your digital pictures (in focus) or send live specimens in a non-crushable plastic jar for free identification. Mail to Peter Mangano or Svetlana Micic at the postal details above.

IPM Guidelines for grains

AgTactic and AgMemo

Other regional DAFWA news updates are available on DAFWA’s website.

Growing Season Outlook

Seasonal climate outlooks are available on DAFWA’s website.

AGWEST Plant Labs

Plant disease diagnostic service 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 our website or the AgWest plant laboratories webpage.

Copyright © Western Australian Agriculture Authority, 2014

The Chief Executive Officer of the Department of Agriculture and Food and the State of Western Australia accept no liabilitywhatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.

Next issue of PestFax – 13 June 2014