Scheduling of Verticillium lecanii and Benomyl Applications to Maintain Aphid (Homoptera: Aphidae) Control on Chrysanthemums in Greenhouses

Abstract

A commercial formulation of Verticillium lecanii (Zimm.) Viegas (Vertalec, Tate and Lyle, Reading, Great Britain) was evaluated to determine its efficacy in controlling the green peach aphid, Myzus persicae (Sulzer), and the chrysanthemum aphid, Macrosiphoniella sanborni (Gillette), on chrysanthemums in greenhouses, its persistence on chrysanthemum foliage, and the effect of benomyl foliar sprays on its activity. A single aqueous spray of Vertalec consistently and effectively controlled M. persicae. However, control of M. sanborni was inconsistent and commercially unacceptable. The half-life of conidia on chrysanthemum foliage at humidity levels ranging daily from ca. 65 to 90% RH was 4.18 ± 0.152 days. Viable spores were detected for as long as 2 weeks after treatment. Benomyl applied as a foliar spray inhibited Vertalec activity when the fungicide was applied 3 days before and immediately before Vertalec applications. Spray intervals of ∼7 days between a Vertalec application and a previous benomyl application appeared to have no deleterious effects on the bioaphicide.