Splash out on glyphosate

Haidee VandenbergheCountryman

Research might have previously showed glyphosate applied with lower water rates was more effective, but trials at the WANTFA Spring Field Day are suggesting otherwise.

GM canola was treated with three glyphosate rates - 30L/ha, 90L/ha and 150L/ha - and two water rates - half the recommended rate and the full label rate.

Those treatments were then applied at only two-leaf stage, only six leaf-stage and both two-leaf and six- leaf.

According to Mike Ashworth, agronomist at the Australian Herbicide Resistance Initiative and WANTFA, the trials at Cunderdin showed keeping water rates robust was important in this particular system.

"A lot of the old research said that the lower the water rate the better for glyphosate efficacy but some of this research, in regards to a crop and a canopy, shows we should keep our water rates up so we get really good coverage on all those weeds," he said.

"There is also the importance of making sure we get those two sprays, the two and six-leaf sprays, on.

"A lot of farmers I surveyed around the State, quite a few of them only managed to get one of them on because the season was so quick.

"It was quite warm and the buds were coming out and they didn't want to put the second one on, but it's really important to try and make sure you get those two sprays on."

A survey of 22,000 hectares of GM canola also revealed there are ryegrass and wild radish survivors.

"The ryegrass would have been because of application and also current herbicide resistance status," Mr Ashworth said. "The radish would be because of an inherent tolerance and also a diverse tolerance across different populations."

Mr Ashworth, who is currently studying for a PhD, is looking at glyphosate resistance evolution in GM canola, said it was imperative to use weed seed management, including harvest weed seed management and windrow burning, to keep glyphosate working.

"There's a lot of work going on to make sure we keep (glyphosate) going really well," he said. "Make sure you control your weed seeds at harvest with the technology and really look after glyphosate because it's the only product of its type and we will never get another one like it."

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