Russian wheat aphid not a major threat to winter cereals, research finds

By Rodney Woods

The more Australian researchers learn about Russian wheat aphid, the more confident they are that the pest does not pose a major threat to winter cereal crops in this country — if growers and advisers understand how to manage it effectively.

The Grains Research and Development Corporation said scientists had been studying Russian wheat aphid under southern Australian conditions and within local farming systems since it was first detected in 2016.

Through research investments by the GRDC, a biological and ecological profile of the pest is being built to provide Australian grain growers with scientifically robust management tactics for the future.

The GRDC investment, Russian wheat aphid risk assessment and regional thresholds, was established to investigate regional risk and management options for the pest.

The collaborative investment is being led by the South Australian Research and Development Institute, the research division of Primary Industries and Regions South Australia, in partnership with sustainable agriculture research organisation cesar.

The regional thresholds aspect of this research has involved the capture of data from a series of trials across south-eastern Australia, which are operated by a number of farming systems groups.

SARDI entomologist Maarten van Helden said the data on infestation levels, symptoms and associated yield would help to determine the regional production risk posed by RWA and the economic thresholds that will guide growers in effective management of RWA, taking into account infestation date, crop type and regional climatic conditions.

“Currently, Australian intervention threshold recommendations are based on overseas research which recommends a spray application when more than 20 per cent of all seedlings are infested up to growth stage 30 and more than 10 per cent of tillers are infested from growth stage 30,” Dr van Helden said.

The Australian trials so far have shown that a considerable amount of RWA population pressure is required before yield loss is incurred.