Investigating IPM tactics to reduce pests and disease incidence and increase marketable yields in organic squash production

Zucchini squash, Cucurbita pepo L., is a high value vegetable crop in Florida. Aphids and the silverleaf whitefly are considered significant pests of squash and are responsible for transmitting plant viruses. Information on organic pest management is limited and sometimes unavailable for many growers. In this study several integrated pest management (IPM) strategies were evaluated to reduce pests and disease incidence while increasing marketable yield in organic squash production.;Objective 1 investigated how the presence of buckwheat and a key natural enemy, Delphastus catalinae, affected whitefly colonization on squash. Whitefly densities were greater on squash when compared with buckwheat. Delphastus catalinae released in exclusion cages in the greenhouse significantly reduced whitefly populations on squash.;Objectives 2 and 3 compared planting arrangements of intercropped buckwheat and squash augmented with D. catalinae, to evaluate effects on pests, disease incidence, natural enemies, and marketable yields in field-grown squash. The treatments included buckwheat alternating (A) on either side of the squash with and without D. catalinae, buckwheat in the middle (B) of squash planted on either side with and without D. catalinae, buckwheat on both sides of squash (C), a bareground treatment, and a mixed varieties treatment. The field experiments demonstrated that aphid densities and insect-transmitted viruses were reduced, while natural enemies were more abundant, in buckwheat treatments compared with bareground treatments. However, the effect of buckwheat on whitefly populations was variable. Ultimately, marketable yields were not significantly different between the bareground treatment and buckwheat arrangements A and B. Furthermore, there were no differences among treatments with similar intercropping tactics when considering the effect of D. catalinae on pest populations, and significant dispersal between plots was observed.;Objective 4 evaluated the effect of insecticides approved for organic use on silverleaf whitefly and D. catalinae in squash. Insecticide treatments included PyGanicRTM, M-PedeRTM, AzaSol RTM, EntrustRTM, and an untreated control. Adult and immature whitefly populations were reduced when applying PyGanic RTM with a delayed release of D. catalinae 3 -- 5 d after spraying. The findings from this study will be useful for incorporating several management strategies for the suppression of aphid and whitefly pests in organic squash production.