13 August 1999

Timely sowing helps rape crop

REMEMBER drilling dates effect on winter oilseed rape establishment, advises Farmacy technical director, David Stormonth, in the light of the ban on Lindane (gamma-HCH).

"Recent comments about lack of insecticide seed treatment increasing flea beetle risk are quite correct." That means everything must be done to optimise plant take, he says.

Even without the pests attentions timely sowing is the key to yield. Four years of farm recording from 1988 to 1991 found relative yields from mid-August, late-August, early-September and mid-September sowings averaged 100, 98, 94.9 and 90%, respectively, Mr Stormonth notes.

"Our own data, derived from farm experience over the past 10 years, shows quite clearly that yield potential can decline by 10% after the end of August. This simple fact, first discovered in the early 1980s, has been proved true again and again.

"Varieties change and hybrids may require different plant populations. But the basic fact of drilling date has not changed."

Timely sowing offers some protection against flea beetle, a more substantial root structure to support high yields and good foliar ground cover to counter pigeon damage and weed competition, he says.

At current prices the 10% yield saved by getting drilling date right would pay for many growers herbicide programmes, he adds. &#42