Effect of mixtures with other products on the efficacyof codling moth granulovirus (CpGV)

The Cydia pomonella granulovirus (CpGV) is one of the most important agents for the control of codling moth in organic farming. In practice, CpGV products are often applied in tank mixtures together with other fungicidal or plant strengthening products to reduce the costs of separate applications. Some of these agents have a high pH value in solutions and therefore may have a negative effect on the stability of the CpGV occlusion bodies. Therefore, we examined whether such mixtures influence the activity of CpGV. In laboratory tests, CpGV was mixed with different fungicidal products (Cuprozin, Netzschwefel Stulln), plant strengtheners (Steinhauers Mehltauschreck, Wasserglas, VitiSan, Cocana, Myco-Sin, HF-Pilzvorsorge, CutiSan, Omniprotect and Armicarb), and other compounds, such as Molke, Düngal, lime sulphur, Ventex and Prev-B-2. After an exposure of four hours, virus activity was calculated from larval mortality determined in bioassays with neonate codling moth larvae. A significant loss of virulence was only found in mixtures under strong alkaline conditions higher than pH 11. Four agents, sodium silicate (Wasserglas) and lime sulphur as well as Omniprotect and Ventex should not be used with CpGV products in tank mixtures.