Timing critical for effective weed control in oilseed rape

UK - February 04, 2008

Unless treated soon, weeds in backward oilseed rape crops will threaten yields and harvest quality, warns Dow AgroSciences.

“There are currently two types of rape crop,” says Rene Pollak, Dow AgroSciences broad-leaved crops technical specialist. "Many crops are dense, well established with good weed control; others are thin, may have received autumn herbicide late or not at all and have many weeds which have continued to grow through the winter."    

Particularly in thin crops, cleavers, mayweeds, creeping and sow thistles all pose a threat to rape yields and harvest quality. They need to be controlled now. 

“If the weather is mild with no frosts expected, then an application of Galera (clopyralid and picloram) now will give excellent control of mayweeds and thistles as well as good suppression of cleavers. But ensure soil conditions are suitable for travel and there is no chance that any pesticide can run-off into water,” advises Mr Pollak. 

Galera should be applied at 0.35L/ha in 200 litres of water with a medium spray quality. Applications can be made until the green buds start to show above the crop, but cannot be applied after GS 3.5. Once the crop reaches GS 3.5 – flower buds raised above the crop canopy – it is too late.