Cover crops and interrow tillage for weed control in short season maize (Zea mays)

Weed competition can cause substantial maize (Zea mays L.) yield reductions . Interseeding maize with cover crops or a combination of interrow cultivat ion and interseeded cover crops are possible alternative methods of weed co ntrol. This study was conducted to examine the potential of interrow cultiv ation plus cover crops to reduce weed density in maize without reducing the grain yield. Field experiments were conducted in 1993 and 1994 at two site s in Quebec to determine the effects of planting 12 cover crops with maize on weed control. Fall rye (Secale cereal L.), hairy vetch (Vicia villosa Ro th), a mixture of red clover (Trifolium pratense L.) and ryegrass (Lolium m ultiflorum Lam), a mixture of white clover (Trifolium repens L.) and ryegra ss, subterranean clover (Trifolium subterraneum L.), yellow sweet clover (M eliotus officinalis Lam), black medic (Medicago lupulina L.), Persian clove r (Trifolium resupinatum L.), strawberry clover (Trifolium fragiferum L.), crimson clover (Trifolium incarnatum L.), alfalfa (Medicago sativa L,), and berseem clover (Trifolium alexandrinum L.) were seeded at two planting dat es, 10 and 20 days after maize emergence. Interrow cultivation was carried out weekly until forage seeding, with a final cultivation being conducted j ust prior to cover crop seeding. Cover crop planting dale did not affect ma ize yields or the ability of interrow tillage plus cover crops to suppress the development of weed populations. Maize yield was less affected by the i nterseeded cover crops under conditions of adequate rainfall. Corn planted in fields heavily infested with weeds resulted in substantial yield reducti ons even when rainfall was adequate. Except for 1993 at l'Assomption interr ow tillage plus cover crop treatments had consistently lower weed biomass w hen compared to the weedy control. Most of the weed control was due to the interrow cultivation performed prior to seeding of the cover crops. The low est weed density occurred in the herbicide treated plots. The ability of in terrow tillage plus cover crops to suppress the development of weeds was af fected by the level of weed infestation, the growing conditions and locatio n. The cover crops provide additional weed control but the interrrow tillag e or some herbicide application may still be necessary. (C) 2000 Elsevier S cience B.V. All rights reserved.