Stimulation of Growth and Yield of Virus-Infected Cantaloupe with Pyrethroids. Thomas M. Perring, Department of Entomology, University of California, Riverside 92521. Charles A. Farrar, Department of Entomology, University of California, Riverside 92521. Plant Dis. 77:1077-1080. Accepted for publication 8 July 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-1077.

Application of pyrethroid insecticides to field-grown cantaloupes had a significant impact on the number of fruit produced per plant but did not influence the rate at which cantaloupes were infected with aphid-transmitted zucchini yellow mosaic potyvirus (ZYMV). Plots that received permethrin had significantly more fruit per plant than control plots, whereas treatment with fenvalerate did not affect yield. In a greenhouse experiment, noninfected cantaloupe plants and plants infected with ZYMV during early vegetative growth, perfect flower production, and fruit set were treated with the same pyrethroid insecticides. Plant response to these treatments was measured as number of perfect flowers, plant weight, fruit weight, and number of fruit. Plants treated with permethrin produced a higher average fruit weight than plants that were not treated. All growth parameters were significantly lower among control plants infected with ZYMV during the vegetative stage; however, the first three were significantly increased by treatment with fenvalerate at that growth stage. These experiments suggest that pyrethroids have a stimulatory effect on plants infected with virus, which is manifested in increased plant growth and yield.