Mechanisms of Weed Suppression in Cover Crop-based Production Systems

Field and laboratory studies were conducted to investigate the mechanisms of weed suppression by cover crops. High-performance liquid chromatograph analysis and a seed germination bioassay demonstrated that rye ( Secale cereale L.) can be leached of its allelochemicals, redried, and used as an inert control for separating physical suppression from other types of interference. In a field study, rye, crimson clover ( Trifolium incarnatum L.), hairy vetch ( Vicia villosa Roth.), barley ( Hordeum vulgare L . ), and a mixture of the four species suppressed the emergence of eastern black nightshade ( Solanum ptycanthum Dun.). Crimson clover inhibited the emergence of eastern black nightshade beyond what could be attributed to physical suppression alone. The emergence of yellow foxtail [ Setaria glauca (L.) Beauv.] was inhibited by rye and barley but not by the other cover crops or the cover crop mixture.