PestFacts WA

Final PestFax newsletter for 2017!

This is the 26th and final weekly issue of the PestFax newsletter for the 2017 growing season. Extra editions may be circulated if extraordinary circumstances occur. PestFax will resume weekly newsletter issues in Autumn 2018. All of this season’s PestFax newsletters can be found at the department’s PestFax newsletter archive.

The PestFax team thanks all those people who took the time to send pest and disease reports in this year. All reports are greatly appreciated and are vital for PestFax to keep readers informed and up to date with the pest and disease situation in their area.

2017 PestFax statistics

This year the PestFax team received 844 reports in total (current to 23 October 2017). This is less than the 1164 total reports received in 2016, but last year the PestFax service played a large role in the state Russian wheat aphid surveillance.

Approximately 227 of these reports were submitted using the new PestFax Reporter app. 163 of the reports submitted via the app had an image or images attached that assisted DPIRD experts with identification and confirmation of insects and diseases.

What were the top five reported diseases for 2017?

There were 178 disease reports received in total by the PestFax team via a variety of means. Powdery mildew was the most reported disease, followed by barley leaf rust. Table 1, below, displays the other diseases that were most commonly reported.

What were the top five reported pests?

The PestFax team received 649 invertebrate pest reports in total. The native budworm moth trapping program was the most reported with reports coming in from both the spring moth trapping survey (221) and field reports (32). Green peach aphids and diamondback moth caterpillars were the insects most reported by the public. The top five insects reported are listed in Table 2, below.

2017 PestFax map statistics

The PestFax map provides a visual display of the pests and diseases reported by the industry. Viewers can choose a host, a disorder and a time period. They can also select a 'Same time as last year' map view to highlight seasonal commonality or differences.

In 2017, an impressive 8826 maps were generated as of 23 October. This number includes every map generated between each dropdown box selection.

Maps that displayed ‘All’ disorders were generated the most with 5888 generated.

Sclerotinia stem rot was the disorder map most specifically generated, followed by powdery mildew occurrence maps. To see what the other top disorder maps viewed were refer to Table 3, below.

For more information on the PestFax service please contact Cindy Webster, PestFax newsletter editor, Narrogin on +61 (0)8 9881 0201.

For information on the PestFax Map or PestFax Reporter app please contact Art Diggle, Senior Research Officer, South Perth on +61 (0)8 9368 3563.

Sclerotinia is being found in canola

• Toodyay
• Moora
• Boyup brook
• Kojonup
• Katanning
• Kendenup
• Frankland
• Kojaneerup
• South Stirlings

A canola stem infected with sclerotinia stem rot. Photo courtesy of: Bec Swift (DPIRD)

The developing sclerotes within the same infected stem. Photo courtesy of: Bec Swift (DPIRD)

Crop protection officer Bec Swift (DPIRD) and plant pathologist Jean Galloway (DPIRD) have found sclerotinia in Hyola 404 and 44Y24 canola crops near Toodyay. The Hyola 404 plants are infected mostly on auxiliary (secondary) stems rather than the main stems while the 44Y24 is showing more main stem infection. Sclerotes are developing within infected stems.

Canola with sclerotinia branch infection. Photo courtesy of: Ravjit Khangura (DPIRD)

Plant pathologist Ravjit Khangura (DPIRD) has found low to moderate levels of sclerotinia in a number of canola crops in Moora, Boyup Brook, Kojonup, Katanning, Kendenup, Frankland, Kojaneerup and South Stirlings. Affected plants predominantly had lateral branches infections with low levels of main stem infections. Symptoms of sclerotinia infections were quite visible in paddocks with affected branches/stems showing bleached appearance.

Ravjit says sclerotinia infection causes premature ripening of plants and therefore poses the risk of premature shattering.

Look out for sclerotes in harvested seed

Harvest has begun for canola, lupin and pulse crops and growers are reminded to check their seed for the presence of sclerotinia sclerotes, especially if they are planning to retain their seed for next year’s crop.

Although the seasonal conditions were less favourable for sclerotinia this season, there is a high probability that the sclerotes may be mixed with the harvested seed in severely affected crops.

Ravjit advises that sclerotes are resting bodies of the fungus that are generally black in color, 2-20mm in length and can survive in soil for more than four years.

Growers are urged to carefully inspect their harvested seed and if they find large number of sclerotes, the seed should be graded. Ungraded seed used for sowing can inadvertently transfer sclerotes into the soil, which can later initiate the disease during the season.

Paddocks with heavy load of sclerotes should be rotated with non-host crops such as cereals for at least for 3-4 years to allow the sclerotes to decompose. Tillage and deep ploughing can also be employed to bury sclerotes to a depth more than 15cm.

Strategies for managing sclerotinia stem rot in 2018

Rotation, tillage and fungicides are currently the best strategies for managing scleronia stem rot, including:

• Long rotations
• Rotating with non-host crops
• Avoiding sowing close to last year’s infected crop
• Using clean seed
• Using foliar fungicide.

Further information about sclerotina stem rot can be found at;

• The department’s Managing sclerotinia stem rot in canola page
• The department’s Protecting WA Crops Issue 5 newsletter Sclerotinia stem rot
• GRDC’s Managing sclerotinia in canola YouTube video.

For more information on canola sclerotinia contact Ravjit Khangura, Plant Pathologist, South Perth on +61 (0)8 9368 3374 or Ciara Beard, Plant Pathologist, Geraldton on +61 (0)8 9956 8504.

Fasciation found in canola and wild radish

• Toodyay
• Goomalling
• South Stirlings

In this canola plant, one of the stems is completely flattened, this condition is called fasciation. This particular stem is also showing sclerotinia infection. Photo courtesy of: Bec Swift (DPIRD)

Fasciation in canola has been observed by crop protection officer Bec Swift (DPIRD) and plant pathologist Jean Galloway (DPIRD) at Toodyay and at South Stirlings by plant pathologist Ravjit Khangura (DPIRD). Jean has also found it in wild radish plants at Goomalling.

Fasciation is a condition where flowering heads and in some instances lower stems get flattened and is also characterised by the presence of abundant flowers and pods on plants.

Fasciation is not common in canola, occasionally some odd plants are seen with this disorder. The actual cause of fasciation is unknown; it could be due to mutation or environmental factors.

Apparently some canola varieties are more susceptible than others to develop fasciation.

Fasciation is unlikely to impact canola yields. There is no known risk of carryover to subsequent canola crops.

For more information on fasciation see the department’s Diagnosing fasciation in canola page.

For more information on fasciation contact Ravjit Khangura, Plant pathologist, South Perth on +61 (0)8 9368 3374 or Jean Galloway, Plant pathologist, Northam or +61 (0)8 9690 2172.

Growers are urged to monitor green bridge to minimise insect pest and plant diseases in crops in 2018

Volunteer cereals forming a green bridge. Photo courtesy of: DPIRD

Growers need to consider potential disease carryover into the 2018 season if wet conditions are experienced during summer resulting in weed and crop regrowth. This vegetation can serve as a ‘green bridge’ for diseases which need a living plant to survive, such as cereal rusts and viruses.

Rust spores are wind dispersed and can go through several cycles during the cropping season. This year, wheat leaf rust was found from Yuna to Esperance, and barley leaf rust and powdery mildew (wheat and barley) were common in central and southern areas. Barley and wheat volunteers can act as a ‘green bridge’ during a wet summer and autumn carrying inoculum of these diseases into the new cropping season.

Weed and crop volunteers can also act as a between-season host for root diseases and aphids. If weeds and/or volunteers are present at the start of the new cropping season, particularly in or adjacent to cropping paddocks, there is a greater risk of early spread of pests, viruses and diseases to newly emerging crops.

Disease management strategies for 2018

Growers need to monitor the green bridge for disease so that timely action can be taken to identify the pathogen and limit the spread and build-up of inoculum.

It is crucial that growers kill weeds and crop volunteers, including those along fencelines, prior to the start of the cropping program to reduce potential pest and disease outbreaks.

Ideally there needs to be a break (a fallow period) of at least two weeks free of vegetation capable of hosting disease or pests prior to sowing. To achieve this, the weeds and volunteers should be sprayed with a herbicide at least four to six weeks before sowing, to ensure weeds are completely dead at planting.

Alternatives to herbicides are to heavily graze or cultivate weeds and crop volunteers which will reduce their potential as a ‘green bridge’ or host of diseases and pests.

In addition to managing the green bridge growers can;

• Sow clean seed. Loose smut widely seen in 2017 especially in the southern and the central regions of the wheatbelt. Therefore using certified seeds treated with seed dressing fungicide is recommended for 2018.
• Get to know the latest disease ratings of your varieties and plan accordingly. Use adult plant resistant varieties. Crop variety guides are available for all grains on the DPIRD website, which document the disease susceptibility for each variety.
• Consider applying in-furrow or seed dressing fungicides to reduce your risk of early infection of diseases such as rusts, net blotches and powdery mildew in susceptible varieties, and rhizoctonia, crown rot and take-all. For more information see the department's Seed dressing and in-furrow fungicides for cereals in Western Australia.
• In case of early disease outbreak, budget for early foliar fungicide sprays where upfront fungicides are not used. For more information visit the department's Registered foliar fungicides for cereals in Western Australia.
• Reduce exposure to stubble borne diseases through rotation and careful paddock planning (to avoid sowing on or adjacent to infected stubble) or stubble management (such as grazing, windrowing, baling, incorporating or burning).
• Earlier sown crops may be more at risk of some foliar diseases such as powdery mildew, net blotches of barley, septoria and yellow spot of wheat so consider later sowing of susceptible varieties and at risk paddocks, or at least plan to monitor earliest sown paddocks closely for disease.

For more information see the department's Control of green bridge for pest and disease management page and the Grains Research and Development Corporation's (GRDC) Green bridge fact sheet.

For further disease forecasts and information on managing specific diseases in 2018 see the department's Crop diseases: forecasts and management.

For more information on crop diseases contact Kithsiri Jayasena, Plant Pathologist, Albany on +61 (0)8 9892 8477, Geoff Thomas, Plant Pathologist, South Perth on +61 (0)8 9368 3262 or Andrea Hills, Plant Pathologist, Esperance on +61 (0)8 9083 1144 or Ciara Beard, Plant Pathologist, Geraldton on +61 (0)8 9956 8504.

Clean augers, field bins and silos prevent insects contaminating grain

On farm grain silos. Photo courtesy of: DPIRD

The 2017 harvest has commenced in WA with the CBH Group tweeting that the first load of canola had been delivered at Esperance on Friday 6 October.

Growers who are yet to commence harvest are reminded that they should check and maintain grain silos before storing this year's harvest to guard against grain storage pests. Regulations prohibit the sale and handling of insect infested grain as well as the spraying of contact insecticides onto grain. The exception is malathion which can be sprayed onto stored grain.

Sealed silos are the preferred system of storage but rubber seals should be checked. Augers, field bins and silos should be thoroughly cleaned of grain residues and treated with a hygiene spray or dust. The ground around storages should be cleared of weeds and rubbish to prevent harboring insects. Old grain resides should be burned or deep buried.

Be aware of withholding periods if you are treating the inside of an empty silo with a suitable insecticide such as malathion or fenitrothion, to provide residual control before the grain is loaded. Non-chemical products like Dryacide® dust need at least two weeks to be effective.

Dryacide is an insecticide and will provide good control for at least 12 months. It is a non-toxic, diatomaceous earth product that must be applied when loading the silo at a rate of one kilogram per tonne. This grain can only be used on your own farm since most central grain buyers will not accept it as it changes the flow characteristic of the grain. However you can store grain even in an open shed very safely using Dryacide.

Fenitrothion is a contaminant in exported grain. If you are using either liquid or dust in the weeks prior to harvest it is recommended you leave it in place for 2-3 days and then wash it off to prevent contamination of any grain that may come into contact with the sprayed surface. It is better to have applied fenitrothion to an empty silo at least two months before harvest to allow it to degrade to harmless substances.

Phosphine is a very effective fumigant gas for sealed storages but it must be held under gas-tight conditions at a lethal concentration for 7-10 days to kill all insect growth stages. Poor fumigation can result in only adult and larval insects being killed giving the mistaken impression that the fumigation was successful. However, the immature eggs and pupae will not be killed so infestations will likely build up again quickly, selecting for resistant populations. Fumigating in an unsealed silo or field bin is an off label use, it is not only ineffective, at best killing adults and larvae, and will lead to strong resistance developing on your farm.

Managing phosphine resistance

Insect populations with weak phosphine resistance have developed in all grain-growing states of Australia largely as a result of poor fumigations. Strong resistance is widespread in the eastern states and has started to take hold in the west, so to help minimise the development of strong resistance to phosphine in WA, use well maintained sealed silos.

Detecting phosphine resistant grain pests early will make eradication possible and will protect your income. To arrange a free resistance test for grain pests contact David Cousins, DPIRD stored grain insect group, South Perth on +61 (0)8 9368 3920.

Farmers keeping grain on farm for their own use, with silos that are not sealed can use aeration or Dryacide or a combination of both as alternative methods to keep insects in low numbers.

Aeration is a tool for creating a low temperature in the silo so that insects breed very slowly. Insects rely on the environmental temperature for body warmth and breed faster in warm conditions. If the temperature is kept below 20°C they will produce less progeny in the storage period. However to stop reproduction, grain temperatures must be kept below 14°C; temperatures below 10°C (difficult in WA) will eventually kill the insects. Failure to follow these strategies may result in the grain having populations of insects and cannot be sold off-farm without fumigation by transferring it to a fully sealed and tested silo.

For more information on stored grain management techniques visit;

• GRDC supported website; Stored grain information hub
• GRDC’s Hygiene and structural treatments for grain storage factsheet.
• DPIRD’s Sealed silos make sense page
• DPIRD's Insect pests of stored grain page.

For more information contact David Cousins, Technical Officer, South Perth on +61 (0)8 9368 3920.

Native budworm moth activity and trapping update

• Bindi Bindi
• Usual trapping sites across wheatbelt

Native budworm caterpillar chewing into a canola pod. Photo courtesy of: Dusty Severtson (DPIRD)

Jessica Florance (Kalyx) reports that native budworm caterpillar numbers have decreased in her canola trial site at Bindi Bindi over the past few weeks. Jessica was finding six to 15 budworm caterpillars per 10 sweeps two weeks ago, four per 10 sweeps last week, and was averaging less than one per 10 sweeps this week.

Many of the volunteer farmers and DPIRD staff who have been trapping this season have packed away their traps because crops are too advanced to be troubled by future moth egg laying. Their efforts in sending in weekly reports to PestFax and providing advanced warning of the budworm threat are greatly appreciated.

Native budworm moths generally move westward looking for less advanced crops as the eastern crops dry out. All late maturing crops and legume pastures should be checked for budworm, especially in areas where moth numbers have been recorded 3-4 weeks ago.

For the locations of budworm moth numbers caught in pheromone traps in recent weeks refer to the department’s Native budworm moth trap numbers 2017.

For more information on thresholds, pesticide options and withholding periods refer to the department’s;

• 2017 PestFax Issue 22 article Latest native budworm moth activity and management advice
• Management and economic thresholds for native budworm page
• Winter/Spring Insecticide Spray Chart 2017.

For more information contact Alan Lord, Technical Officer, South Perth on +61 (0)8 9368 3758 or +61 (0)409 689 468