The Impact of Rye Cover Crops on Weeds, Insects, and Diseases in Snap Bean Cropping Systems

We investigated the impact of a cereal rye mulch, either alone or interseeded with red clover, on weeds, insects and diseases of snap beans. Yield loss and poor growth in plots with rye mulch and red clover was attributed to poor kill of rye, herbicide application, and soil compaction during mowing. Initial weed suppression by rye mulch was similar to conventional tillage, although supplemental manual weed control was necessary in the rye plots later in the season. Early dandelion infestation from wind-blown seeds was a problem in rye mulch in 1995. Rye mulch had a variable impact on insect populations. The reductions in populations of potato leafhoppers and thrips feeding on snap beans in the rye plots were related to the smaller size of the plants. Although leaf-feeding insects such as bean leaf beetles and southern corn rootworm were not affected by management system, there was more leaf damage in the rye plots than in the control treatments. Levels of white mold were lower in the rye mulched plot, possibly due to the less dense canopy structure or reduced soil contact. To make rye mulch a feasible weed management tactic, soil compaction needs to be minimized and additional N fertilizer may be required.