Aim for best practice against blackgrass, despite late harvest

The past season has seen many farmers make considerable investment in tackling blackgrass, including increased use of fallow land, spring-sown cereals and break crops
The past season has seen many farmers make considerable investment in tackling blackgrass, including increased use of fallow land, spring-sown cereals and break crops

Regardless of harvest delays, farmers seeking to stay on top of blackgrass should not cut corners in their control strategies, says Dow AgroSciences.

The past season has seen many farmers make considerable investment in tackling blackgrass, including increased use of fallow land, spring-sown cereals and break crops, according to Dow AgroSciences’ cereal weed control expert Stuart Jackson.

“All the evidence of recent years shows that the only way to prevent blackgrass building up in fields is to use a full programme of cultural and chemical controls starting with a stale seedbed after harvest.

“Some farmers may be anxious about the time a stale seedbed can take. However, unlike previous seasons, there is plenty of moisture in the ground to encourage swift germination of grass weeds,” says Mr Jackson. “What’s more, it is well-established that later drilling is another important part of an effective blackgrass strategy.”

Seedbed preparation is important. Ploughing may be necessary after oilseed rape or a break crop, particularly where blackgrass control in these crops was poor or where product labels stipulate ploughing prior to sowing the next crop. However, where cereals follow cereals it is better to minimally till to keep blackgrass seeds near the surface where stale seedbeds and residual chemicals can work best, especially in a year where control levels within the cereal crops have been better.

Once the new crop is drilled, an effective pre-emergence residual is the next vital step in the blackgrass control programme.

“All our trials data shows that missing this step out is a false economy,” says Mr Jackson.

Dow AgroSciences recommend treatments based on flufenacet and pendimethalin. However, it is important to ring the changes in terms of mode of action to delay the development of herbicide resistance to these vital active ingredients.

The final step to complete the programme is a post-emergence contact spray, such as Dow’s UNITE (pyroxsulam + flupyrsulfuron-methyl).

“Timing is absolutely critical for this final step to be really effective,” says Mr Jackson. “The key is to treat small, actively growing blackgrass plants. These are the most sensitive to treatment and control will be most effective.

“Time and again, our trials show that delaying treatment leads to poor control compared to early treatments.”

UNITE not only offers blackgrass control as effective as any treatment on the market, it also delivers control of a range of broad-leaved weeds and gives farmers flexibility in their rotation as it has no restrictions on cultivations or sowing after harvest.