The extension of Biscaya would give brassica growers a stronger hand, said Bayer campaign manager for horticulture Dr Bill Lankford. "It should be particularly helpful to calabrese growers needing to control peach-potato and mealy cabbage aphids this summer," he said.

Independent trials at Oxford Agricultural Trials showed better control and greater persistence. Two days after application to four-leaf-stage calabrese, peach-potato aphid control from Biscaya amounted to 95 per cent, and a fortnight after application it was 73 per cent.

From pirimicarb plus non-ionic wetter, control was 48 per cent and 31 per cent respectively. Similar differences for control of mealy cabbage aphid were also seen.

The extension of Biscaya's label covers use in broccoli/calabrese, cabbage and cauliflower crops.