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SPRING HERBICIDE USE REACHES UNSUSTAINABLE LEVEL
Date added: 29/08/06 |
Over reliance on Spring herbicides is increasing at alarming rate despite new evidence of their ineffectiveness in certain conditions and major concerns about growing resistance levels, according to the latest statistics from ProCam’s 4cast agronomy system.
Use of ALS inhibitors in Winter Wheat rose to 95% of fields being treated this current growing season compared to 70% last year. More worryingly, applications in March and April more than doubled from 10% to 23% and over the same period, resistance also doubled.
“There is such a high proportion of crops being treated with ALS inhibitors now, every time you use them you are simply selecting for resistance,” Dr David Ellerton says.
“The problem is compounded by the fact that there is clear evidence that Atlantis (iodosulfuron and mesosulfuron) and other herbicides provided very poor control when they were applied in Spring this year.”
The cold wet March, with temperatures half a degree colder than average, virtually stopped crops growing and impaired the products’ chemical action, Dr. Ellerton believes, but the application of sulphonylurea group herbicides also created damage in following crops.
“The bottom line is that Spring applications of herbicides offer poorer control on established weeds and of course it means your crops have been competing with these weeds for far longer than they need have been, so there are yield implications too. They also get in the way of optimum fungicide and PGR application dates.
“4cast shows that this season, over 60% of Atlantis sprays were applied during February and March and I would say this trend has now reached an unsustainable level. We are seeing severe control and resistance problems across the country.”
Growers are trying to do too much in the Spring and neglecting Autumn control and cultural control methods.
“The only way to move forward is for producers to target herbicides at the most competitive weeds and maximise their use of cultural and agronomic control methods,” Dr Ellerton urges.
“We need to think more about an integrated crop management approach. For example, delaying drilling can allow you to miss the peak blackgrass emergence in the Autumn but you must make the correct varietal choice appropriate to individual field circumstances to avoid a drop in yield.
“Use as wide a range of herbicide groups as possible and include a pre-emergence spray wherever you can. Use pre-drilling and early Autumn herbicide treatments appropriately and use Spring applications only as a last resort.” |
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