Dry September makes top-up spray vital for ryegrass

Dry conditions throughout September mean a top-up herbicide spray may be needed to control ryegrass in winter cereals.

Pre-emergence herbicides may not have performed to their optimum due to the lack of moisture in the soil, and have increased the importance of applying a post-emergence herbicide.

Stuart Jackson, from agrochemical company Dow AgroSciences, says ryegrass has become an increasingly challenging weed to control and action this autumn will be vital to prevent it becoming an even greater problem.

Active ingredients

Broadway Star – pyroxsulam and florasulam

“It’s essential to follow up with a post-emergence treatment, applied to small actively growing weeds,” he said.

See also: Dry start to September hinders winter crop establishment

Ryegrass is highly competitive and populations can build rapidly, particularly in the autumn. In addition, it has joined the army of weeds showing signs of herbicide resistance, so preventing populations from building up will be crucial.

Mr Jackson says the company’s Broadway Star will control ryegrass along with a range of grassweeds including wild oats and bromes.

The ideal application timing is at 1-3 leave stage of the grassweed while it is actively growing.

“The addition of a residual partner will help extend the period of control to sweep up any late emerging weeds,” added Mr Jackson.

“Where the target is ryegrass we recommend a mix based on pendimethalin or prosulfocarb, ideally alternating with the active used at pre emergence spray. Consider using a higher rate where no pre-emergence treatment was made,” he said.