Implications for Winter Oilseed Rape due to Neonics Ban

The recent two-year ban by the EU of all neonicotinoid-based insecticide seed treatments in oilseed rape has brought home how complacent farmers could become about regular crop monitoring and early spraying.

The pests which these seed treatments controlled were cabbage stem flea beetle (CSFB) and aphids. Before the existence of seed treatments, regular monitoring of the crop from emergence was
advised, looking for characteristic ‘shot hole’ feeding of cotyledons and first leaves.

If cotyledons were damaged, then the early attack often required two sprays to allow the crop to establish. Once it had reached a reasonable size, it could withstand the leaf feeding damage. Adults which escaped the early control measures needed separate treatment in the autumn.

Much evidence suggests that foliar sprays are as effective as seed treatments, through it may involve two sprays – with the first applied soon after emergence, if beetles move in early. The control of this pest without the seed treatment is possible – but just a little more inconvenient.