Weather break aids mosaic probe
From the August 2006 edition of Agriculture Today.
Winter rain has allowed crucial research into the potentially devastating wheat streak mosaic virus (WSMV) to go ahead.
NSW Department of Primary Industries staff have sown trials and will continue to monitor crops throughout the State in a bid to reduce the impact of the virus.
First detected in NSW three years ago, WSMV has been found in all wheat growing areas of the State and last year cut yields of some early wheat crops in the Central and South West slopes by up to 80 per cent.
Growers who find the virus have been advised to contact their local NSW DPI agronomist.
In resistance trials, sown last month near Coolah, NSW DPI researcher Steven Simpfendorfer is testing risk levels of commercial wheat varieties, including durum wheat.
“We basically don’t have any solid data on how the virus will have impact in Australian conditions and we aim to generate that information through this trial and supporting research,” Dr Simpfendorfer said.
“Oats, barley and triticale were also planted and while we don’t expect them to be as susceptible, this trial will confirm their resistance levels.
“From our research we plan to develop information growers can use next year and give them some indication of the best options.”
Another target of the WSMV trial is the wheat curl mite, responsible for spreading the virus.
According to Dr Simpfendorfer the virus can’t spread without the presence of the mite.
“Wheat curl mites need what we call a green bridge to reach crops. Spraying out any volunteer wheat and grass around the edge of your crop will reduce the likelihood of those mites moving in,” he said.
“We are testing chemical controls on the mite. USA data indicates that insecticides just don’t work on the wheat curl mite but we need to confirm whether a similar situation exists here.”
Early sown wheat crops are more susceptible to infestation by wheat curl mite because they are planted when the mites are active.
Wheat curl mites thrive in temperatures ranging from 24 to 28 degrees Celsius. They become dormant once temperatures drop below 10 degrees Celsius.
The trial was sown into a volunteer wheat crop infected with WSMV and researchers have sprayed the existing self-sown crop with herbicide to force the mites and associated virus onto the emerging trial crops.
With additional funding from the Grains Research and Development Corporation, research into the management of WSMV and the wheat curl mite is supported by NSW DPI laboratory trials in Wagga Wagga and Tamworth and field trials at Coolah, Young, Nangus and Ganmain.
For more information about WSMV go to www.dpi.nsw.gov.au/aboutus/resources/factsheets/primefacts/wheat-streak-mosaic
Contact Dr Steven Simpfendorfer, Tamworth, (02) 6763 1100, steven.simpfendorfer@dpi.nsw.gov.au
