THE POSSIBILITY OF MUTUAL CONTROL OF STEM MINING WEEVILS AND POLLEN BEETLE IN OILSEED RAPE

Stem weevils and pollen beetle are significant pests that attack oilseed rape crops after winter hibernation. Correct timing of insecticide application is a key point in control of both pests. The aim of this research is whether the mutual control of both pests is possible in order to reduce insecticide input. The two-years experiment was set up according to the EPPO guidelines in random block design in four replications with nine different treatments. The optimal treatment period was determined by monitoring the occurrence and population density of stem weevils using yellow water traps. The decision threshold for pollen beetles was determined by beating terminal inflorescences into trays. The use of insecticides against rape stem weevils and pollen beetles is possible if thresholds are exceeded at the same time. All insecticides applied against stem mining weevils increased rapeseed yield, and in the absence of treatment, the average loss of oilseed rape seed yield was 37%.