Keep seed treatments for RWA effective

Keep seed treatments for Russian Wheat Aphid effective


Farm Online News
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Farmers may be tempted to protect against Russian Wheat Aphid with a seed treatment but they may be increasing risks of resistance.

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Elia Pirtle, Cesar, says farmers need to be sure there are sufficient Russian Wheat Aphid numbers around to cause economic damage before using seed treatments so as not to increase the risk of resistance from overuse.

Elia Pirtle, Cesar, says farmers need to be sure there are sufficient Russian Wheat Aphid numbers around to cause economic damage before using seed treatments so as not to increase the risk of resistance from overuse.

RUSSIAN Wheat Aphid (RWA) inspires fear among Australian farmers with good cause.

One of the world's most economically important pests of cereal grain, since first being discovered in Australia in 2016, RWA has spread through SA, Victoria, Tasmania and NSW and authorities have given up attempts to eradicate it from Australia, instead focusing on management strategies to limit damage.

Unlike other aphids which cause damage through feeding, RWA injects toxins into the plant that causes acute symptoms that can lead to potentially significant yield losses.

However, one entomologist has said farmers need to be judicious with treating RWA and not to overuse seed treatments to reduce the risk of resistance to treatments such as the neo-nicotinoid group of products.

Speaking at the Grains Research and Development Corporation update in Bendigo earlier in the month, Elia Pirtle, of pest monitoring organisation Cesar, said farmers needed to assess whether RWA was at economically damaging thresholds before putting out seed treatments.

She said while it was tempting to put out a prophylactic seed treatment each year to prevent the risk of RWA, in the long run this just put undue pressure on the chemistry within the seed treatments if there were not the economic levels of RWA to treat.

"I urge growers to use neo-nicotinoid treatments judiciously, according to the regional risk and using the Find, Identify, Threshold and Enact (FITE) approach."

At present thresholds for economic damage have not been done for Australian conditions so international standards are being used.

As well as seed treatments, Ms Pirtle said insecticides were effective in controlling the pest, while beneficial species, such as parasitic wasps also reducing numbers.

Ms Pirtle said research had showed a green bridge over summer allowed RWA to build up and said researchers were currently working on guidelines for green bridge control to limit the risk.

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