Effects of insecticidal seed treatments and foliar sprays in winter oilseed rape in autumn on insect pests and TuYV infection

In this study, the effect of the four different insecticides Karate Zeon (a.i. lambda-cyhalothrin), Elado (clothianidin + beta-cyfluthrin), Fortenza Force (cyantraniliprole + tefluthrin) (only 2015), and Lumiposa (cyantraniliprole) (only 2016 and 2017) on the insect autumn pests Delia radicum, Psylliodes chrysocephala, and aphids (mainly Myzus persicae) and Turnip Yellows Virus in winter oilseed rape was investigated in 3 years of field trials. The results showed that the effects of the Elado seed treatment on P. chrysocephala depend on the time of migration of adults. Due to delayed immigration of beetles into the field in 2015/2016 and 2017/2018, there was no clear effect of the seed treatment on the number of larvae per plant. In contrast in 2016/2017, the beetles colonized the crop in early September, and the number of larvae was significantly reduced by Elado. Cyantraniliprole and clothianidin seed treatments seem to support crop emergence independent of insect pests assessed. Spraying of the pyrethroid Karate Zeon in autumn significantly decreased the number of larvae in all years. Also the number of next-generation beetles was significantly reduced only by Karate Zeon. In all years, the aphid infestation was significantly reduced only by Elado seed treatment. The infection rate by TuYV was very high in all years and only slightly reduced by Elado seed treatment. There was only minimal occurrence of Delia radicum in all years. Cyantraniliprole products did not show any influence on the assessed insect pests in all years. There was no significant effect of any treatment on yield, but in 2015/2016 and 2016/2017, the highest yield was obtained in the Elado seed treatment.