Wait until soils are cooler and wetter before applying the residual herbicide propyzamide (as in Propose and Flomide), Interfarm has advised growers.

Although the product can be used from 1 October to control cereal volunteers, annual meadow grass, blackgrass and a number of other weeds, conditions may not yet be suitable for it to work properly, warned technical manager, David Stormonth.

“Judging the correct timing for propyzamide this autumn will not be easy. Soil temperatures are several degrees above normal. We recommend that application is delayed until soil temperatures are cooler.”

Soil moisture deficits are also too high in many areas, he said. “Recent rainfall may have alleviated the problem in some areas, but large parts of eastern England still have significant deficits.”

Waiting until frosts and rain reduce oilseed rape canopy cover may be worthwhile, as this will help improve spray coverage, he added. In the meantime, he suggests using a suitable contact graminicide to control some grass weeds.

Propyzamide can be used up until the end of January and Dr Stormonth recommends using the higher dose rates in order to gain maximum persistence – in oilseed rape Propose is recommended at 1.4 or 1.7kg/ha and Flomide at 1.7 or 2.1 litres/ha.