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POSTERS: Integrated pest management

Effects of cover crops, rotation, and biological control products on soil properties and productivity in organic vegetable production in the Northeast
Robert Larkin - USDA ARS.

The potential benefits of different cover crops, biological control amendments, and vegetable rotation on soil chemical and biological properties, crop development and yield, and disease development in organic vegetable production, as represented by legume (green snap bean), cucurbit (yellow summer squash), and solanaceous (sweet pepper) vegetable crops, were evaluated in a multi-year field trial in Maine. Cover crops evaluated included winter rye/hairy vetch, mustard green manure, a multi-species mixture (8 crops), and a fallow control. All cover crops improved biological properties compared to fallow soil, but had only marginal effects on soil chemical properties. The multi-species mixture and rye/vetch cover crops were associated with earlier emergence in beans and squash. All cover crops improved yield in beans and squash by 7-13%, but only the cover crop mixture increased yield for pepper (by 7-11%). Minimal crop diseases were observed throughout these studies, and biological control amendments, which included commercial formulations of Streptomyces, Trichoderma, and Bacillus spp., in general, did not positively affect yield, but reduced powdery mildew on squash and leaf necrosis on beans by 10-28%. Vegetable rotation also affected yield, with beans yielding 8% higher following squash vs. pepper, squash yielding 15% higher following beans vs. pepper, and pepper yielding 11% higher following beans vs. squash. These results help define specific management practices to improve organic vegetable production and provide useful information and options for growers.