Evaluation of module-sown companion plants as a method of controlling cabbage root fly

Summary

A novel technique for controlling cabbage root fly was tested. Companion plants of either birdsfoot trefoil (Lotus corniculatus), red clover (Trifolium pratense) or yellow trefoil (Medicago lupulina) were sown into modules together with calabrese (Brassica oleracea var Italica). The presence of companion plants subsequently reduced cabbage root fly egg-laying by up to 48% and reduced root damage considerably. Companion plant species did not affect egg-laying in this trial. Although, financially, this technique compares very favourably with an alternative strategy of applying fleece, further refinement is needed to improve the survival of companion plants on a commercial field scale as they were particularly vulnerable to damage by steerage hoes, which are used commonly in organic systems.