Prioritise grass weeds, Dow AgroSciences urge

Many UK farmers face the latest campaign to control blackgrass and other grass weeds and setting priorities for the current crop and next season will be vital, according to Stuart Jackson of Dow AgroSciences.

After a long, wet cold winter period soil temperatures are rising above the 6°C needed for active growth and for contact acting herbicides to be effective. There is still time to control weeds, but priorities must be set and products chosen with an eye to cost control and efficacy next season.

“Top priority, has to be tackling blackgrass and sterile brome,” said Jackson.

Growers who drilled early last autumn and applied residual treatments should look to get a contact acting product on in the coming week to complete a normal programme.

However, such growers are the minority. Many drilled later and weather conditions prevented any herbicide treatment.

“The focus needs to be on applying contact materials that will control the blackgrass as it begins to grow away in warmer conditions. Options for residual treatments are very limited with many now being precluded by date or crop growth stage,” he said.

“In later drilled winter wheat, both weeds and crop have poor growth so the contact action of pyroxsulam will deliver effective control of blackgrass and sterile brome.”

The prolonged cold spell may well trigger spring germinating wild oats, which will also need control. Where ryegrass threatens, Mr Jackson suggests there is more time to treat.

With yield forecasts declining, there needs to be an increased focus on economic treatment. However, treatments in the next few weeks also need to look forward to next season. Many growers with blackgrass problems will be looking to use a winter oilseed rape break crop.

“Treating the preceding wheat crop this late in the season means careful attention must be paid to label recommendations for cultivation following harvest. The pyroxsulam-based products have no requirements for cultivations post-harvest. In fact, oilseed rape can be established through Autocasting safely after any of our products are used. Other products have cultivation restrictions that will impair weed control efficacy in a following oilseed rape.”