Pre-emergence herbicides will become increasingly important, believes David Ellerton, technical director of the ProCam Group.
“Most of the weed control problems encountered on farms are where a pre-emergence herbicide hasn’t been used,” he says.
Relying on Atlantis alone is a risky strategy, he warns. “Not only have there been more cases of resistance found, it also has to be matched to the weed germination pattern and spraying opportunities. We know that temperature is very important to its effectiveness.”
Pre-emergence treatments can reduce the blackgrass burden by up to 80%, as well as improve the overall efficacy of grass and broadleaved weed programmes, adds Dr Ellerton.
“They provide insurance against the lack of an appropriate post-emergence spray window, give more choice with post-emergence choices and help with resistance management.
“Considering that we are losing some of the post-emergence options, they’re going to be relied on more.”
Better grain prices should encourage growers to try out various options this season, he believes. “There’s an argument for stacking some of the pre-emergence options, to see how they perform.”
Experience with Defy last year was very positive, reports Dr Ellerton. “On blackgrass, used at the 4-litre rate and mixed with trifluralin, we saw 70-80% control. But we also mixed it with pendimethalin and pendimethalin mixtures, as well as other established treatments such as Crystal and Liberator, to look for alternative partners.”
That work will continue in earnest this year, he stresses. “The best results came from trifluralin, so we need to find others. Trifluralin also has the advantage of being cheap and totally unaffected by resistance.”
On ryegrass, Defy mixed with chlorotoluron gave “exceptional” results. “We were also pleasantly surprised by Defy’s brome activity and anticipate that it will be an important product for annual meadowgrass control, especially since we won’t have IPU for much longer.”