Wheatbelt grain growers and agronomists concerned about an increase in glyphosate resistant annual ryegrass have been urged to sign up as soon as possible to take part in a collection and resistance testing program.
A total of 150 samples will be collected and tested before harvest from the Central Midlands, eastern Wheatbelt and Great Southern, as part of a project between the Department of Agriculture and Food and the Grains Research and Development Corporation.
Department senior research officer Sally Peltzer, who is coordinating the collection, said a similar project undertaken in the south eastern Wheatbelt this year confirmed glyphosate resistance was on the rise.
“Another 14 glyphosate resistant annual ryegrass populations were found, bringing the total for the eastern south coast to 69,” Dr Peltzer said.
“The samples were tested at two rates of 1.5 and 3 litres per hectare, with 26 per cent either showing or developing resistance to the smaller dose and 20 per cent to the larger dose.”
The new testing program will examine the same rates, while participants will also have the opportunity to test and pay for other herbicide tests.
Dr Peltzer encouraged all growers to test for resistance and adopt an integrated weed management strategy to avert the risk.
“If there were ryegrass still alive after two applications of glyphosate in GM canola crops this year, there is a fair indication they are resistant,” she said.
“For other paddocks, such as those with a 10 year or longer history of no-till and those where fences and firebreaks have been repeatedly sprayed with glyphosate, patches of problem weeds would have shown up as green amongst dead plants during the year.
“Problem paddocks should be harvested using harvest weed seed management techniques, like narrow windrow burning, chaff cart and seed destructor to stop most of the resistant seeds from re-entering the seedbank.”
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