Microclimate manipulation of entomopathogenic nematodes and fungi to enhance efficacy against a novel life stage of plum curculio (Conotrachelus nenuphar) in Michigan tree fruit production

Eastern US tree fruit growers, facing limitations on pesticide inputs largely brought on by the passage of the Food Quality Protection Act (1996), are seeking alternatives for managing plum curculio (Conotrachelus nenuphar Herbst) in organic, IPM, and conventional orchards. Researchers have demonstrated the virulence of entomopathogenic nematodes (families Steinernematidae and Heterorhabditidae) and fungi (Metarhizium anisopliae and Beaveria bassiana) to various life stages. Beauveria bassiana and Steinernema riobrave were found to suppress adult plum curculio emergence through augmentative applications targeting larval life stages in field experiments, however efficacy was limited across application timings. In 2009 and 2010, we investigated the effect of microclimate manipulation on entomopathogenic fungi and nematodes targeting plum curculio larval life stages in Michigan apple and cherry orchards. Microjet sprinklers were installed in pre-existing irrigation hoses located within the driplines of trees and irrigated soils for one hour -1, 0, 1, 3, and 5 d from applications of B. bassiana and S. riobrave. In 2010, we tested the efficacy of B. bassiana when incorporated into jute mats which were placed within the driplines of apple and cherry trees and received irrigation via microjet sprinklers.