23 August 2002

Scots OSR warning

POOR aphid control last year and the return of flea beetle mean Scottish winter oilseed rape growers are being urged to use Chinook (imidacloprid + betacyfluthrin) seed treatment this autumn.

Although Chinook was on trial on many farms, most crops did not carry the dressing, says the SACs Andy Evans. But its effectiveness was highlighted by unprecedented peach-potato aphid (Myzus persicae) migration last August, he notes.

"Approved insecticide sprays, used in the absence of Chinook, were often ineffective due to MACE and kdr aphid resistance. Several rape crops failed to establish in the absence of the dressing."

Although trapping suggests aphids are scarce, the picture was similar last year and populations can rocket, warns Dr Evans.

Irrespective of aphid control, he advises including Chinook in winter rape programmes, particularly in the Borders due to the reappearance of flea beetle and cabbage stem flea beetle. &#42