WEED AND CORN (ZEA-MAYS) RESPONSES TO A HAIRY VETCH (VICIA-VILLOSA) COVER CROP

Field studies were conducted in 1990 and 1991 to determine the effects of com planting date and hairy vetch control method on the efficacy of fall-planted hairy vetch as a weed-suppressive cover crop for no-till com. Glyphosate controlled hairy vetch when applied at the early bud growth stage (April), but hairy vetch residue provided no weed control compared to the weedy check. Mowing was not an effective means of suppressing hairy vetch at the early bud stage. Untreated hairy vetch reduced weed biomass 96% in 1990 and 58% in 1991 but reduced yield over 76% in April-planted com. There was no competition of untreated hairy vetch with com when com planting was delayed until May or June (mid- or late-bloom growth stages of hairy vetch). Com planted in May into untreated hairy vetch yielded similarly to com planted in a no-cover weed-free check.