In the absence of neonicotinoid seed treatments, control will be reliant on the use of foliar sprays of pyrethroids. Any decision to apply an insecticide must be based on a risk assessment.
The oilseed rape (OSR) pest cabbage stem flea beetle (CSFB) is widespread in the UK and northern Europe. Since 2013, when neonicotinoid-treated seed was withdrawn from use in OSR, management of this pest has become more challenging.
OSR is most vulnerable at emergence, when the crop can grow more slowly than it is being eaten. The growing point of the crop can also be destroyed.
Resistance to pyrethroid insecticides has been confirmed in the UK CSFB population. Both target-site resistance and metabolic-based resistance, the latter conferring strong resistance to pyrethroids, have been confirmed.
Resistance pressures mean it is essential to use integrated pest management (IPM) approaches to minimise the use of insecticide sprays. In particular, it is important that treatment thresholds are followed.
Where a spray is deemed necessary, full recommended field rates should be applied. If control is poor, pyrethroid sprays should be avoided.