Effects of plant growth-promoting rhizobacteria on bell pepper production and green peach aphid infestations in New York

Plant growth-promoting rhizobacteria (PGPR) are known in various cropping systems to increase plant growth and vigor, as well as induce resistance to pathogens and pests. A commercial soil amendment containing a mixture of two species of Bacillus PGPR (Bacillus subtilis and Bacillus amyloliquefaciens) was evaluated for impact on germination and initial growth of bell pepper plants, efficacy against the green peach aphid, Myzus persicae Sulzer, and yield enhancement. Studies in the greenhouse revealed that pepper germination rate and dry weight of seedlings grown with or without Bacillus spp. did not differ significantly. In the field, the PGPR did not significantly reduce aphid populations compared to control plants, whereas imidacloprid was highly effective. An increase in yield compared with control plants was observed in the 2003 season, but not the following two seasons. Aphid pressure was high in 2003, and plants grown in the presence of Bacillus spp. exhibited substantial tolerance to aphids. That is, there were significantly higher populations of the green peach aphid on both control and PGPR-treated plants compared with imidacloprid-treated plants. However, fruit yield in the Bacillus spp. treatment was significantly greater than yield in the control treatment and similar to yield in insecticide-treated plots. Bacillus PGPR could be useful in a M. persicae management program for pepper plants grown in locations with consistently high aphid pressure.