Aphid will ride the wind to Queensland
WHAT'S that? It's a bird, it's a plane, it's... a Russian Wheat Aphid riding the breeze to a cereal crop near you.
The aphid was detected on the Liverpool Plains in northern New South Wales in late-2018 and research entomologist Maarten van Helden from the South Australian Research and Development Institute predicts it will be found in Queensland's winter cereal crops within the next few seasons.
Speaking at an aphid information session in Toowoomba on January 21 as part of a surveillance survey stretching through northern NSW and into southern Queensland, Mr van Helden warned growers to be alert but not alarmed.
"While (the aphid) is a high priority pest, it is manageable and the best thing growers and advisers can do is regularly monitor crops for signs of the pest,” he said.
"There are very distinct plant symptoms associated with (the aphid) and early detection will give growers time to make informed, timely, cost-effective decisions about the appropriate management strategy for their situation.”
He said if any suspected Russian Wheat Aphids were found, they should be sent to the Department of Agriculture and Fisheries at Toowomba for identification so, if confirmed, State-based chemical permits can be enacted.
Department senior entomologist Hugh Brier, based at Kingaroy, said there aphid had two key identifying features.
One was its "elongated green body”, the other the aphid's absence of siphunculi (cornices), colloquially known as its "honey tubes or exhaust pipes.”
Mr Brier said the department agrees with Mr van Helden's assessment that the aphids are on their way.
"It's a matter of when it comes and then mitigating it,” he said.
He said the aphids will "ride the winter winds”, which blow from the south and south-west.
If you notice ladybirds or hover flies in your cereal crops, then it's likely you may have aphids, Mr Brier said, as ladybirds and hover fly larvae are key predators.
Another give away is the presence of leaf streaking or leaf rolling on cereal crops and grasses, indicative of infection.
Department principal entomologist Dr Melina Miles said certain weather conditions will likely precipitate the aphid's arrival.
"It is most likely that we will see the aphid in winter cereal crops in Queensland in a season that favours an aphid outbreak: a wet autumn-mild winter (supports the build up of the aphid) and a dry spring (favours aphid impact on crops),” she said.
Dr Miles agreed with Mr van Helden's caution that growers be alert but not alarmed.
"The aphid is a very manageable pest,” he said.
"Research being done has shown that crop loss accumulates slowly, so there is time to detect and control potentially damaging infestations before crop loss occurs.”
The Grains Research Development Corporation has advised that eliminating the "green bridge” of volunteer cereals and weeds will reduce the aphid's host plants and put growers on the front foot.
The host plants enable aphids to persist from one growing season to the next.
In 2017, the corporation released a fact sheet containing tips and tactics for combating the Russian Wheat Aphid, available at grdc.com.au/TT-RWA.
The aphid was first detected in 2016 and is Australia's latest broadacre crop pest.
It is now established in South Australia, Victoria, Tasmania and New South Wales.
For formal identification, send samples to Melina Miles, DAF, PO Box 2282, Toowoomba, Queensland, or email Melina.Miles@daf.qld.gov.au.