Straw on the soil significantly reduces weed infestation under no-tillage system. The potential of winter cover crops and their management timing in reducing weed infestation in maize crop were studied in Canoinhas, Santa Catarina, Brazil, in 2003/04 and 2004/05. In the first experiment, 6 winter cover crops were investigated: oilseed radish, black oat [ Avena nuda], rye, ryegrass [ Lolium sp.], intercropped among black oat and common vetch [ Vicia sativa] and among oilseed radish, black oat, rye, ryegrass and common vetch. These cover crops were slashed down at three different times before maize sowing (1, 10 and 25 days). In the second experiment, the potential to reduce weed infestation was investigated in the 6 cover crops previously mentioned, plus the common vetch. The straw of ryegrass and from intercropping among the 5 species used had a high capacity to suppress weed emergence and dry matter production, while oilseed radish straw showed low weed suppression potential. The winter cover crops slashed down next to maize sowing decreased the weed infestation.
