Issue Number: 07Date: 27/06/2014

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

ContentsBarley net blotchYellow spot on wheatRedlegged earth mitesBarley powdery mildewSclerotinia in canolaWhite leaf spot in canolaAfrican black beetleWoolly bear 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: PestFax@agric.wa.gov.au or use the online “make an on-line report” link.

Barley net blotchThere are reports by agronomists to Department of Agriculture and Food (DAFWA) staff in the central agricultural region that they are seeing some early net blotch on barley. The farmers are beginning to spray at tillering crop growth stage. Agronomists from the northern agricultural region also report net blotch in barley and that the farmers are keeping it under control.

There are two types of net blotch (net type and spot type net), and both are stubble and seed borne. Infection and spread of both diseases are favoured by wet conditions and it is most evident following periods of rainfall. It will cause the greatest yield loss in paddocks that are re-sown to barley without a break-crop.

DAFWA Plant Pathologist Kith Jayasena says the risk could have been avoided or minimised by adopting measures that include appropriate selection of paddocks (i.e. not seeding barley on barley stubble), choosing varieties with a good resistance profile (see page 9 Barley Variety Sowing Guide), burning or burying stubble where practical to reduce disease carry-over, avoiding early sowing or using excess nitrogen, applying potassium fertiliser to deficient soils (<50 parts per million) 6-8 weeks after barley crop emergence and using registered seed dressing fungicides. If

required, farmers can apply a fungicide spray, and a follow-up spray may be necessary in high rainfall areas.

Further information could be obtained from following DAFWA site: Managing net-type net blotch and spot-type net blotch in barley in Western Australia

Yellow spot on wheatReports from agronomists in the central agricultural region to DAFWA staff indicate that levels of yellow spot infection have been increasing in recent weeks on many wheat crops in the central agricultural area. The disease levels have been particularly high and widespread this season on continuous wheat rotations. Many of these crops have been sprayed with fungicides.

Spraying for yellow spot or septoria nodorum blotch - DAFWA Plant Pathologist Ciara beard said these leaf spot diseases are hard to distinguish and appear in wheat as irregular or oval-shaped spots that initially are small and yellow, but enlarge to form brown dead centres, with yellow edges. Typically, a badly affected leaf will die back from the tip as lesions merge, reducing the photosynthetic area and causing premature leaf death. These diseases are particularly a problem in continuous wheat crops in stubble retention farming systems as they are stubble-borne. These diseases have the capacity to significantly reduce yield (by up to 30%) and grain quality in medium-high rainfall areas or other areas receiving above average rainfall this growing season. For wheat after wheat, when there is high disease pressure prior to stem elongation, it may be economic to apply fungicide at or prior to early stem elongation (Z31, first node) particularly in medium to high rainfall areas. A second spray may be required at or after flag leaf emergence based on the above considerations.

A range of foliar fungicides are registered for controlling these diseases. For further information please see 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)

Redlegged earth mitesRedlegged earth mites (RLEM) have continued to be troublesome and required control in some crops and pastures throughout the Western Australian grain belt. This particularly applies to late sown crops and pastures where colder weather has slowed plant growth. In other situations, where higher than anticipated levels of mites are still present, some growers are incorporating insecticide into their post emergent herbicide applications or pasture manipulation spraying programs.

Reports by agronomists to DAFWA staff in the central agricultural area indicate the RLEM are still requiring control in areas near Brookton, Narrogin and Merredin.

Tiny second generation RLEM are now commencing to be seen alongside larger mature mites in many central and southern grainbelt areas. These smaller mites are likely to be the offspring from the parent hatching of RLEM which mostly occurred after the 26 April and/or 8 May opening rains.

For further information see the following DAFWA links Diagnosing redlegged earth mites and the Autumn Winter Insecticide Guide 2014

Barley powdery mildewDAFWA Plant Pathologist Kith Jayasena reports that he found powdery mildew in a Baudin barley crop at tillering stage (sown mid-May) near South Stirling. There was no fungicide seed dressing

applied. This follows the earlier identification of powdery mildew spores by Kith in a network of spore traps deployed through the South Stirling region (see Pest Fax No.2 23 May 14). Kith recommends that growers in the region check their barley, particularly paddocks sown from early to mid-May and susceptible to very susceptible varieties seeded with or without any compromised fungicide. He also suggested that foliar fungicides be used at low rates, (could be added with post emergence herbicide spraying), as yield losses can be higher if powdery mildew infection occurs at the tillering stage. Kith said growers should avoid using compromised fungicides at any cost. For further information see the webpage: Management of barley powdery mildew in 2014 - fungicide resistance

Sclerotinia in canolaDAFWA Plant pathologist Ciara Beard has found sclerotinia apothecia in a canola crop at Ellendale (southeast of Geraldton). Apothecia are the little cream coloured mushrooms of roughly 0.5cm in diameter that germinate from sclerotes and spread ascospores that cause sclerotinia infection in canola, lupins and other hosts such as wild radish and capeweed.  The apothecia found this week were found in a gully in a heavy loam paddock covered with a good layer of wheat stubble which has helped to retain moisture. The majority of apothecia appeared light orangey/brown in colour which signifies they are at least a couple of weeks old. The canola is at nine plus leaf (cabbage) stage and has no current disease symptoms. Airborne ascospores generally only infect canola petals so infection doesn’t develop until crop flowering. The paddock where the apothecia were found was previously infected with sclerotinia around three years ago. The apothecia find follows an earlier occurrence at the same site by Agrarian agronomist Chris Pinkney on 4th June that was not able to be corroborated at that time. In most cases, apothecia generally don’t germinate until there is complete canopy coverage from canola plants as that enables the maintenance of soil moisture and the development of a suitably humid environment. This would be around cabbage to green bud stage or later, depending on the variety. Apothecia development is more likely on heavy soils that stay moist for longer.

Plant pathologist Ravjit Khangura commented that the fungus Sclerotinia sclerotiorum can survive as sclerotia in the soil for many years.  The seasonal conditions allowed early production of apothecia in some areas this season. Growers need to assess their risk in particular they need to look at the paddock history of their current canola crop. The high risk paddocks are the ones that had either canola or lupins in rotation over the last three years. Growers are advised to carefully consider their risk and be prepared to apply fungicide to combat Sclerotinia this season. Currently registered fungicides for management of sclerotinia in canola include Prosaro®, Iprodione (e.g. Rovral® Liquid) and Procymidone (e.g. Sumislex®, Fortress®).  Fungicides should be applied as per label recommendations. Ravjit says further updates will be provided as the season progresses.

Spray timing for sclerotinia – Crop flowering stage, along with weather conditions are the main determinants on when to spray for sclerotinia. DAFWA research has shown the optimal time for a single fungicide application in most years is 20 - 30% flowering (when 15 - 20 flowers are open on the main stem). In a high disease risk situation where two sprays may be warranted, application at 10% flowering followed by a second at 40% flowering is a strategy worth considering. Application before 10% flowering (10 flowers open on main stem) is not recommended. Sclerotinia infection and spread requires moist conditions so if it is dry, disease progression in the crop will slow. Hence being flexible and monitoring future rainfall patterns is important in the timing of fungicide application; applying close to the next rainfall event is a good strategy.

For more information on managing sclerotinia stem rot in canola please see the webpage Managing sclerotinia stem rot in canola.

White leaf spot in canolaRyan Pearce (Glencore Grain) reports seeing low levels of white leaf spot in a canola crop around Williams. The disease was found in a Crusher canola crop at the six leaf stage which had been treated with the seed dressing Maxim XL™. The affected paddock was about 400m away from 2012 canola residues.

DAFWA Canola Pathologist Ravjit Khangura reports seeing low levels of white leaf spot in some focus paddock samples and in a canola crop around Moora. Ravjit says white leaf spot can be recognised by small, necrotic, off-white to greyish spots on leaves 1-5 millimetres (mm) in diameter. The lesions are often surrounded by a dark margin. As disease progresses several lesions join together to form large necrotic areas. Severe infection on the leaves may cause premature defoliation. Cool (10-15 degrees Celsius) wet conditions favour rapid disease development. The fungus can infect stem and pods later in the season. White leaf spot is usually considered to be of minor economic importance in canola in WA due to its sporadic occurrence and low levels of inoculum, however, tight canola rotations are likely to increase build-up of inoculum.  No fungicides are registered for the management of white leaf spot.

African black beetle Agronomists have reported to Southern Agricultural Region DAFWA staff that large numbers of African black beetles (ABB) have been found causing damage to cereal crops and sown pastures in some south coast areas. Damage seems to be most prevalent where summer perennial grasses such as kikuyu grass has been present nearby. 

Description - The adult beetles are shiny black (brown when newly emerged) and cylindrical, up to 12 mm long.  The soil dwelling larval stage, which is mostly found in late spring, summer and early autumn feeding on the roots of perennial grasses, is a curl grub ("C" shaped), up to 25 mm long with a brown head and 3 pairs of legs.  These look very similar to, but are usually larger than, the more common pasture cockchafer larvae.  At this time of the year most of the population are in the adult black beetle stage and may be found on the soil surface or under the soil to a depth of 150 mm.  Populations of the beetles are more common in higher rainfall areas closer to the coast and where there has been an abundance of summer perennial grasses such as kikuyu and couch.

Beetles are more likely to be seen walking on the soil surface at night. 

Control - A density of around 2 to 6 ABB per square meter can cause problems especially in newly sown ryegrass pasture.  There are no chemicals registered specifically to control ABB in pasture or cereal crops in WA, but pasture seed treated with imidacloprid for redlegged earth mites may have some efficacy on ABB.  Chlorpyrifos (e.g. Lorsban®) is registered on cereals, pastures and forage crops for some pests and rates as high as 1.5 L/ha (of products containing 500 g/L active ingredient) may be effective against ABB.  The following cultural control methods have been suggested to improve the chance of getting pasture /crop establishment:

-  Increased seeding rate, where ABB are known to be in high numbers.

-  Avoid drill rows where possible so the beetles do not have easy access along row workings.

ABB should not be confused with the black-headed pasture cockchafer mentioned on some chemical labels as it is not a known pest in WA, but is only a pest in Eastern Australia. 

Further information on identification, photos and management strategies are available on the

webpage Diagnosing African black beetle

Woolly bear caterpillarsA farmer near Binnu reports that he has seen woolly bear caterpillars in a wheat crop in numbers of around 3 per square metre, the caterpillars are not causing any damage as most are dead or dying as a result of a recent insecticidal application to control other pests. In the weedy areas along the edge of paddocks and roadside reserves adjoining the wheat crop, where the caterpillars are feeding on broadleaf weeds, the numbers are much higher with up to 16 caterpillars per square metre.

Woolly bear caterpillars are a common occurrence throughout the rural and Perth metropolitan areas, however in some years when conditions are favourable their numbers can increase considerably and they become much more noticeable. They are easily controlled by insecticides and rates that are used on other common seedling caterpillar pests. For more information on Woolly bear caterpillars see PestFax No.6 20 June 14

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

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 below.

Svet Micic, DAFWA Albany 444 Albany Highway Albany WA 6330Email: svetlana.micic@agric.wa.gov.au Phone: +61 (0)8 98928591 or +61 (0) 427 772 051

Peter Mangano, DAFWA South Perth3 Baron-Hay CourtSouth Perth WA 6151Email: pmangano@agric.wa.gov.au Phone: +61 (0)8 9368 9753 or +61 (0) 404 819 534

Intergrated Pest Management 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 – 04 July 2014