Adoption of Amyelois transitella (navel orangeworm) monitoring and management practices across California tree nut crops

In California, the most significant insect pest of almonds and pistachios is the navel orangeworm, Amyelois transitella (Walker) and is a pest of walnuts. This pest attacks the nuts and infestation is associated with aflatoxin contamination. While there are multiple integrated pest management (IPM) practices available, anecdotal evidence suggests that not all tools are equally utilized. To understand current industry practices and barriers to adoption, the authors surveyed tree nut growers and industry professionals across 7 University of California Cooperative Extension meetings in California’s Central Valley. Findings indicate that as managed acres decreased, participants were less likely to report using as many IPM tools, and pest control advisers reported higher use of multiple practices compared to orchard owners and managers. Key barriers to adoption varied by practice and included high economic costs, low labor availability, environmental conditions, and/or timing constraints. Many respondents were skeptical of the efficacy of mating disruption, a relatively new strategy compared to other IPM tools. Finally, a cluster analysis identified thirteen aggregate grower profiles. Groups primarily differed in their use of monitoring practices, although some groups were also less likely to use sanitation or pesticides. Two groups were distinguished as “early adopters” through their use of mating disruption and/or ovibait traps. These findings document variability in adoption of IPM practices for A. transitella in tree nuts. Identification of the primary barriers and constraints for specific grower groups will inform research and extension efforts to further promote adoption of key IPM strategies.