Numbers of aphids flying are gradually decreasing and will continue to do so. From next week suction-traps will be emptied weekly rather than daily.

APHID-BORNE VIRUSES IN OILSEED RAPE (TuYV)

Aphid flight into crops (primary infection)

Numbers of peach–potato aphid are a little above average and these can potentially colonise oilseed rape. If there has been good control of aphids to this point and they can’t be found in crops, the danger is probably passed.

Aphid movement within crops (secondary spread)

Conditions are still permitting aphid development, reproduction and movement within crops and, if aphids can be found easily, measures to control them (and hence reduce the risk of virus spread) remain justified.