Cover crops support arthropod predator activity with variable effects on crop damage during transition to organic management

Across the Mid-Atlantic United States, organic grain growers are interested in minimizing tillage to reduce management costs and detrimental effects on soil. Organic cover crop-based rotational no-till (OrgCCRT), in which cash crops are no-till planted into a mat of rolled cover crops, may meet grower objectives. However, growers may not adopt OrgCCRT if the system provides habitat for pests, especially during the transition to certified organic management when financial risk may be high. We studied the effects of OrgCCRT on predatory arthropod activity-density, diversity and community composition during the three-year transition to organic management. We also assessed biological control potential of the system, pest activity-density, and damage by invertebrate pests to two, no-till-planted cash crops, corn (Zea mays L.) and soybean (Glycine max (L.) Merr.). A mixture of hairy vetch (Vicia villosa Roth) and triticale (x Triticosecale Wittmack), and cereal rye (Secale cereale L.) preceded corn and soybean, respectively, as winter cover crops, which were terminated by rolling on three dates (early, middle, and late). Predatory arthropod activity-density, richness, and the relative predation index increased by the third year of organic management in rolled hairy vetch-triticale. Lower caterpillar densities in hairy vetch-triticale and lower slug density in both rolled cover crop treatments correlated with significantly greater predator activity-density, regardless of year or planting date. Delaying cash crop planting date resulted in greater cutting, chewing and slug damage in some crop years. Time in organic management augments predatory arthropod activity-density and diversity in OrgCCRT systems, thus contributing to suppression of invertebrate pests and crop damage.