With winter wheat drilling under way across the UK, growers are being advised to use autumn herbicide programmes combining active ingredients with different modes of action to protect crop establishment and yield potential.
Holly Pratt, herbicides technical specialist at ADAMA, said delaying drilling until late October remains best practice for difficult grassweeds such as black-grass, ryegrass and brome. The delay allows early weed flushes to be removed before drilling into a stale seedbed.
However, after successive wet autumns, many growers have already drilled. Pratt warned that pressure on cash flow after two years of drought could also encourage some businesses to reduce crop-protection inputs.
“That would only exacerbate the threat from grassweeds, as any plants that go unchecked in the autumn will have a significant impact on crop yield at harvest,” she said.
She advised growers to build programmes around additional active ingredients with different modes of action. Diflufenican, pendimethalin and chlorotoluron can improve the performance of aclonifen- and cinmethylin-based programmes, according to independent trials.
In six independent trials, including work by ADAS and NIAB, adding pendimethalin to a tank mix of Proclus® (aclonifen) and Liberator® (flufenacet and diflufenican) improved black-grass control by 10–16%, ADAMA said.
Pendimethalin can be used at pre- or post-emergence by applying ANTHEM (400g/litre pendimethalin) with other actives, or through TOWER (250g/litre chlorotoluron, 40g/litre diflufenican and 300g/litre pendimethalin), Pratt said.
Where cinmethylin and pendimethalin have already been applied pre-emergence, a post-emergence application of TOWER can extend the weed-control window and help keep crops cleaner during early development, she added.
“The efficacy offered by a tank mix containing several actives is often greater than the sum of its individual chemistries,” Pratt said. “Timing, rate and accuracy of application are just as important as the actives being used.”
She urged growers to work with a qualified agronomist and make control decisions early: “Once weeds emerge, you are chasing the problem rather than preventing it.”
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