Russian Wheat Aphid (RWA) was recently discovered in South Australia and subsequently in Victoria. RWA has since been declared endemic in Australia, meaning it will not be eradicated but must instead be managed. RWA has not yet been found in New South Wales.

Russian Wheat Aphid has the potential to cause significant damage to cereal crops. Vigilance is required to detect the pest, primarily based on plant symptoms. While a number of insecticide options are available, their use should be based upon Economic Thresholds and the preservation of beneficial insect predators, which will play an important role in the management of RWA.

With the current cold, damp conditions in southern NSW, the risk of damage during winter 2016 is fairly low; however the chance of infection will increase as temperatures rise during spring. RWA is likely to require ongoing management into the future.

Left untreated, RWA can cause significant damage to wheat and barley crops, plus act as a vector for viruses including Barley Yellow Dwarf Virus (BYDV) which affects oats, barley, wheat and triticale. Much of the damage associated with RWA comes from toxins injected into the plants while feeding. Untreated feeding damage has been reported to cause up to 80% yield loss in wheat and 100% yield loss in barley. For this reason, vigilance is required when inspecting cereal crops.

GRDC is promoting a management plan for RWA based on the acronym F.I.T.E.

FIND

Diagnosis of RWA infestation will most likely be via plant symptoms, which include leaf curling, plus white, yellow and red stripes which run the length of the leaf.

Photo credit: Michael Nash

IDENTIFY

RWA are longer and thinner than other aphids found in southern NSW, plus they have a number of key diagnostic features which can only be determined with a hand lens. Affected plants and any associated insects should be reported to NSW DPI.

Photo credit: PIRSA

RWA Reporting Tool: http://goo.gl/forms/4fPlYm0PV6MXBk933

THRESHOLD

Spray only upon exceeding an Economic Threshold of: - 20% infected plants prior to tillering - 10% infected plants once tillering has begun.
These thresholds are based upon international experience, but may be updated for Australian conditions once local experience is gained.
Spraying aphid populations below the economic threshold, risks not only wasting money, but potentially undermining the long term efficacy of available insecticides.
Control options include the following emergency permits, based on international experience: - Chlorpyrifos (Lorsban) - Pirimicarb (Pirimor)
Seed treatments containing Imidacloprid (Emerge/Gaucho) have been shown to provide suppression for up to 6 weeks.Various insecticide treatments used on other aphid species are being trialled, but may not be as effective on RWA.
Various insecticide treatments used on other aphid species are being trialled, but may not be as effective on RWA.

ENACT

Use an Integrated Pest Management (IPM) approach which considers the effects of beneficial predators in controlling RWA.
Beneficial insects include: ladybirds, parasitic wasps, lacewings, damsel bugs and hover flies.
RWA populations are determined by environmental conditions, as are many other aphid species, preferring warm, dry conditions. However, RWA are reported to tolerate cold conditions better than many other aphid species in southern Australia, based on a tendency to shelter in leaf rolls.
Recent heavy rainfall and cold weather in South Australia has been shown to reduce aphid populations by up to 50%. Drying winds can also significantly reduce populations.

LINKS TO OTHER RESOURCES:

Pest Facts – Russian Wheat Aphid Update http://www.pir.sa.gov.au/research/services/reports_and_newsletters/pestfacts_newsletter/russian_wheat_aphid_update

NSW Biosecurity Update http://www.dpi.nsw.gov.au/content/biosecurity/plant/russian-wheat-aphid

GRDC Management Plan https://grdc.com.au/Media-Centre/Media-News/South/2016/06/Gloves-are-up-in-sustained-FITE-against-Russian-wheat-aphid