3 July 1998

Insecticide as a seed treatment?

A NEW angle to pest control in field-scale vegetable brassicas is being evaluated at HRI-Kirton.

After being trialed as a pre-planting drench and in a mixture with compost last year, imidacloprid insecticide is being evaluated as a seed treatment for controlling aphids in brussels sprouts in 1998.

"Results from last year showed that both imidacloprid treatments worked very well and kept sprouts clean for up to 14 weeks after planting," says HRI entomologist Rosemary Collier. "The idea of the seed dressing is to see how few follow-up sprays are needed to keep crops free from trouble."

On untreated plots 72% of sprout plants had some aphids on, but they were on only 5% of plants grown from treated seed.

The crop is at an early stage, it will not be until August that the HRI will have a better idea of the level of persistence and degree of control provided by the new seed treatment. By then scope for reducing the number of sprays needed for effective aphid control should be known.