Early season plant cover supports more effective pest control than insecticide applications

The authors studied the interaction of pest management practices and cover cropping on weed biomass, pest pressure, crop damage and yields, and predator activity in corn-soy-corn and soy-corn-soy rotations at a Penn State University research farm over three years. Pest management strategies with or without a cover crop were as follows: preventive pest management (prophylactic neonicotinoid insecticide + fungicide seed coatings), integrated pest management (scouting + apply pesticides if thresholds are met, no seed treatments), or no pest management.

Early season vegetative cover (both from cover crops and weedy vegetation) promoted activity-density of surface-active arthropod predators and was the most effective strategy for reducing pest density and damage in these corn and soy rotations. Seed treatments reduced some early plant damage, but were ineffective against grubs or slugs, decreased predator activity-density, and had no impacts on crop yields. The no seed treatment IPM blocks received one at-planting application of a pyrethroid insecticide for scarab beetle grubs over the three years of the experiment, which did not effectively control the grubs, disrupted predator activity, and had no yield benefit. The authors concluded that the best management strategy for this crop rotation is encouraging biological control by planting cover crops and avoiding broad spectrum insecticides wherever possible.