31 August 2001

OSR growers must pay attention to weeds & diseases

WITH many oilseed rape crops sown early into moist warm seed-beds, growers need to pay extra attention to weeds and diseases this year, warns Liz Williams of CPB Twyford.

"I have nothing against sowing early, but it just means you have to be very careful to keep on top of your weed and disease control programmes."

Banks Cargill crop protection director Steve Wolff, who is also agronomist at Barton Hill Farm, agrees. "You really need to take the first opportunity to apply metazachlor or a metazachlor/trifluralin mix as a useful lower cost combination against broad-leaved weeds."

However, with good crop growth to compete with the weeds that could be all that is required this season, he suggests.

There is plenty of phoma inoculum waiting to cross the bridge from last seasons stubbles to infect leaves on this years crops, adds Dr Williams.

The most significant advantage of sowing early is that in the larger plants expected that infection will take longer to move to the stems where it eventually causes canker. That could widen the treatment window.

"The earlier you drill the higher the phoma risk," says Mr Wolff. "If you get early infection it may even be necessary to spray twice in the autumn." The main fungicide choices are difenoconazole and flusilazole. &#42