ABSTRACT
A research programme was initiated to confirm the effectiveness of, and extend familiarity with, a method of cabbage root fly control which involves minimal use of insecticide. Several workers throughout Europe co-operated. The method requires the application of chlorfenvinphos or chlorpyrifos to a brassica seedbed at 10 or 20 kg ha-1 and is relevant only to brassicas raised in a seedbed and transplanted. Where cabbage root fly attack was sufficient to affect growth, yield increases of up to 303% were recorded. Seedbed treatments compared favourably with standard treatments, where these were included, and in one case significantly outyielded a standard treatment. Reduction of root damage was generally only slightly less in seedbed treatments than in standard treatments.
Seedbed treatment, previously used mainly in summer cauliflowers, compared favourably with standard treatments in protecting brussels sprout crops, which have a longer growing season and, therefore, test the persistence of effectiveness more fully.
Seedbed treatment with chlorpyrifos did not adversely affect parasitism of cabbage root fly larvae and pupae, but parasite numbers were reduced by corresponding chlorfenvinphos treatments and by field treatments.
Two experiments, in which plants were raised in peat blocks, confirmed a previous observation that insecticide application rate can be reduced by following the principles of the seedbed method, notably by earlier post-emergence application.
