GROWERS SHOULD consider applying a contact graminicide before blackgrass gets too large for residual herbicides to work, BASF has advised.

Mild weather throughout October means grass weed germination and canopy development has been rapid and growers need to act quickly, said the firm’s oilseed rape product manager, Diane Heath.

“At the moment it is just too warm for residual herbicides to work. It is important growers apply a contact-acting graminicide as soon as they can, as there could be a long wait until conditions are suitable for residuals to work “

ADAS oilseed rape expert, Peter Gladders agreed. “Residual herbicides will not work terribly well while it remains warm. We need some overnight frosts to help get soil temperatures down.”

Some very forward crops are already starting to run, so it may also be more effective to delay any growth regulator until mid-stem extension, rather than early, he noted.

To control grassweeds, Mrs Heath suggests growers use Aramo (tepraloxydim) at 1 litre/ha, but are reminded it has a cut-off date in winter oilseed rape of the end of November or nine true leaves of the crop, whichever occurs first.

Because it is a “dim” herbicide, Aramo can be effective in grassweed populations with enhanced metabolism and target site resistance, BASF claimed.