Get mapping grass weeds

CEREAL GROWERS should start planning their 2004/5 blackgrass control campaign now, according to experts.

The very dry autumn of 2003 meant many sterile seedbeds did not work and chemical control programmes may not have performed as well as growers had hoped, said Dalgety technical agronomist Colin Lloyd.

“You need to make the connection on a field by field basis between the chemicals applied and the associated cultivation programme with the patches where grass weeds are still thriving,” he said.

Crop-walking and mapping fields and parts of fields where weed control has been poor should be done during June when most grass weeds are showing, advised Mr Lloyd.

Where herbicide resistance is suspected, growers should also collect mature seed from poorly controlled patches for resistance testing.

“Patches of blackgrass, ryegrass and wild oats are often put down to spray misses,” said Rothamsted weed scientist and resistance expert Stephen Moss.

“But when looked at more closely and with record and mapping data to hand then herbicide resistance is often the more likely culprit.”

The key to getting on top of the problem, he advised, is to build up a history of spray records.

“Successful farmers also use mapping as part of an increasingly diverse armoury against difficult grass weeds,” said Dr Moss.

“They plough more and deeper, perhaps only grow first wheats and have often gone in for far more spring cropping.”