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 front other types of interference. In a field study, rye, crimson cloves (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 atone, 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.