Controlling pollen beetle with the natural agent Surround

Meligethes spp. (pollen beetles) can cause major damage to oilseed rape crops. Organic and extensively farmed stands are especially at risk, since the use of insecticides on them is prohibited. Moreover, the pollen beetle's increasing resistance means that non-chemical treatment options could also become important for conventional oilseed rape cultivation in future. Agroscope has tested numerous natural agents in field trials for efficacy against the pollen beetle. The kaolin-containing product Surround showed good efficacy and usability in practice when used in combination with a wetting agent containing rapeseed oil. From 2011 to 2013, Surround was compared under PEP conditions with conventional insecticides and an untreated control in a total of 10 large-plot trials, where it exhibited a statistically significant efficacy of 50–70 % vis-à -vis the untreated control. The duration of effect was approx. five days. With one treatment, the use of Surround increased grain yield by an average of 10 %, whilst the chemical-synthetic insecticides produced an average increase in yield of 17 %. A second treatment after a gap of 6–10 days improved the yield for both methods of control by an additional 7 % on average. In oilseed rape fields that are well supplied with nutrients, a treatment with Surround is worthwhile in economic terms as soon as the control action threshold of 3–5 beetles per plant has been reached.