AN INCURSION of one of the world’s most damaging crop pests, the Russian wheat aphid (RWA), in South Australia has the nation’s biosecurity sector busily formulating a plan to minimise harm to crops.
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Executive director of Biosecurity South Australia Will Zacharin said there had been confirmed sightings of the aphids at a number of locations in the state’s Mid North, around Strathalbyn, south of Adelaide and in the Upper South East near Bordertown.
RWA can cause almost complete crop destruction if left uncontrolled, injecting the plant with toxins that retard growth.
Mr Zacharin said if untreated the aphids could cause 70pc loss of yield in wheat and 100pc yield loss in barley crops.
Prior to the sightings, Australia was the last major wheat producing nation not to have the aphids.
Complicating the matter is the fact there is no registered insecticide for controlling Russian wheat aphid in Australia, although insecticides are used effectively in other crop producing nations.
Mr Zacharin said the South Australian government had issued a front line response emergency permit for the use of chlorpyrifos, the insecticide that is used to control the pest in other countries, over 20,000 hectares.
After that, Plant Health Australia (PHAU) has applied to the Australian Pesticides and Veterinary Medicines Authority (APVMA) for an emergency permit for the use of two insecticides.
Executive director of PHAU Greg Fraser did not name the two products prior to official confirmation of the emergency permits coming through, but said he was hopeful the permits would be issued this week.
Mr Zacharin urged the entire industry to closely monitor crops for the pest.
“It is really important to have surveillance, so we are calling on farmers and agronomists to keep an eye out.”
Andrew Weidemann, chairman of Grain Producers Australia, urged growers even in areas distant from the current sightings to pay particular attention during crop inspections.
“Russian wheat aphid can be difficult to spot, it can be camouflaged on the plant canopy, so farmers need to look closely.”
He also said plant hygiene was critical.
“The aphids can transfer on clothing, so if you’ve been in infected areas make sure you do not spread the aphids elsewhere on your clothes.”
Mr Zacharin said biosecurity officers across the nation were running workshops on how to spot the aphids and the appropriate response.
“We’re asking anyone who spots the aphids to also phone in on our hotline so we can map where they are spreading to, we’re pretty sure they are more widespread than we have picked up so far.”
“Ideally people will treat the aphids as quickly as possible, we’ve already sprayed in the Mid-North, and kill rates of 95pc have been recorded, so the good news is the aphids can be controlled.”
In terms of identification, Mr Zacharin said the Russian wheat aphid was relatively easy to differentiate from other aphid species.
“It is a different colour, it is green and it is much narrower with more of a point at its head than a rounded end, however even if people are not sure if it is RWA or not, they should let someone know.”
In terms of plant symptoms, Mr Zacharin said the signature sign of RWA was obvious leaf curl, with white, yellow or reddish markings on the leaves.
The damage is caused differently to the problems caused by the green peach aphid (GPA)\, which principally damaged broadleaf crops by infecting them with the beet western yellows virus (BWYV).
“The damage with RWA is not through a virus, it is a through a toxin the aphid itself spreads.”
Mr Zacharin said while it was concerning to have a new and exotic incursion, he was confident Australia could manage the problem pest.
“Across many countries, it is effectively managed through spray regimes, the problems come if the spray does not go out early enough, numbers can multiply quickly.”
Mr Zacharin said entomologists were unsure as to how RWA made its way to Australia.
“The most likely theory is that it has flown in on trade winds, perhaps from Africa.”
“There are precedents of RWA travelling large distances on prevailing winds.”
Meanwhile, primary industry departments in other states are on red alert for the pest.
Biosecurity Victoria will hold a meeting in Horsham tomorrow advising the industry on how to deal with the aphids.
Mr Weidemann said a lot of behind the scenes work was going on to ensure the pest was managed appropriately.
“It’s been frantic at present trying to get things in place.”
He said in the future breeding would play a role in managing RWA.
“There is RWA resistant germplasm in the Australian cereal breeding pipeline, but obviously that is a slow process, so it will be at least three or four years before anything hits the market.”
