The goal of the research in my thesis was to determine whether the efficacy of augmentative releases of entomopathogenic fungi and nematodes for plum curculio control in apple and cherry orchards can be improved via microclimate manipulation and soil texture consideration. To meet this goal, the effect of soil moisture delivered through micro-sprinkler irrigation and the estimation of soil texture on entomopathogens was investigated in field efficacy experiments. Field trials indicated mixed levels of efficacy by entomopathogens against plum curculio, with only one application timing interval decreasing plum curculio emergence compared to untreated controls, and demonstrated a trend in which plum curculio emergence was greater in irrigated versus unirrigated treatments. In addition, plum curculio soil-dwelling life stage activity was studied in laboratory experiments to provide additional support for field study findings. Laboratory studies focused upon the influence of soil texture and moisture potential on plum curculio burrowing depth and pupation rates. At low moisture levels, plum curculio were not found in the pupal lifestage, while higher moisture treatments had significantly greater numbers of plum curculio found in the pupae. At low moisture levels, plum curculio depth was greatest in sandier soil treatments, while under high moisture treatments plum curculio were found at greater depths in clay-dominated soils. This research was aimed at providing producers with broader opportunities to adopt alternative pest management tactics to control plum curculio, including the implementation of entomopathogens as well as cultural and mechanical methods.
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