Social, cultural, and chemical avenues for pear psylla management

Molly Sayles

Pear psylla (Cacopsylla pyricola) is the most economically damaging pest of pears in the Pacific Northwest (PNW), with particularly severe impacts in Washington’s Wenatchee Valley. Its phloem-feeding nymphs produce honeydew, which damages fruit, stresses trees, and complicates orchard management. Integrated pest management (IPM) strategies that combine selective insecticides with cultural controls can effectively suppress populations while conserving natural enemies, yet adoption has been limited in the Wenatchee Valley. This dissertation examines ecological, behavioral, social, and outreach factors influencing pear psylla management and IPM adoption. Semi-structured interviews with Wenatchee Valley-based early adopters and stakeholders from other PNW pear-growing regions revealed structural, social, and cultural barriers to IPM, including risk perceptions, monoculture landscapes, a complex decision-making network, and limited Extension support. Follow-up interviews indicated gradual adoption driven by peer communication and economic pressures. Multi-year stakeholder surveys evaluating a phenology-based IPM program with diverse outreach strategies, including newsletters, field days, discussion groups, and grower panels, demonstrated adoption among engaged growers, particularly larger operations, and highlighted the importance of peer-driven outreach in promoting awareness, trialability, and perceived benefits of IPM. To further inform IPM strategies and understand pear psylla behavior, egg white protein, SmartWater, and fluorescent powder were evaluated as marking materials for mark-capture and mark-release-recapture applications. Egg white and fluorescent powder showed promise for pear psylla mark-capture studies, with detectability for about two weeks, and limited transfer between individuals; however, egg white was the most practical in an orchard-wide setting. These chapters integrate biological, behavioral, social, and applied perspectives, collectively advancing the understanding of IPM adoption by revealing the hesitancies of Wenatchee decision-makers, and pear psylla behavior, by providing a tool for researching dispersal. This dissertation benefits the PNW pear industry by delineating IPM success stories from other regions and pinpointing areas to target in the Wenatchee stakeholder network to increase IPM adoption, while establishing a research method to address commonly cited barriers to IPM adoption in the Wenatchee Valley.

Social, cultural, and chemical avenues for pear psylla management

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