Having the correct seed-bed conditions and depth of drilling are the crucial factors in deciding whether to spray a pre-emergence blackgrass herbicide spray in wheat, rather than the amount of rainfall, according to Bob Mills of Frontier.

“My advice is simple; familiarise yourself with field conditions. Is the seed-bed well-rolled and not too cloddy? Is the depth of drilling correct? Once you are comfortable with the conditions there is no need to hold back from the use of an effective pre-emergence,” he said.

If seed-bed conditions were right a pre-emergence herbicide spray for grassweeds   could be extremely effective, he said.

“But if conditions are not right, which may well be the case for those who drilled early on cloddy and forced seed-beds, it may be prudent to wait for a peri- or post-emergence application.”

Increased blackgrass dormancy was likely to mean a protracted period of germination this season, he added. “So I would recommend a good residual component to the pre-emergence grassweed control strategy.”

BASF’s Clare Tucker suggested the pendimethalin in Crystal would add persistence to flufenacet’s short-term activity against grassweeds. “That’s valuable in an autumn where germination will be longer because of the longer dormancy, and where soil conditions are cooler than we’ve had in the past two years.”