Winter Cover Crop Growth and Weed Suppression on the Central Coast of California¹

Abstract

Winter cover crops are increasingly common on organic and conventional vegetable farms on the central coast of California between periods of intensive vegetable production. A 2-yr study was conducted in Salinas, California, to quantify (1) cover crop and weed biomass production during cover cropping, (2) early-season canopy development of cover crops, (3) weed seed production by burning nettle during cover cropping, and (4) weed emergence following cover crop incorporation. The cover crops included oats, a mustard mix, and a legume/oats mix that were planted in October and soil-incorporated in February. Weed and cover crop densities, early-season cover crop canopy development, above-ground weed and cover crop biomass production, seed production by the burning nettle, and postincorporation weed emergence was evaluated. Mustard produced more early-season biomass than oats and the legume/oats mix. There were no differences in above ground biomass production by the cover crops at the end of their growth period. Suppression of weed biomass and seed production of burning nettle was greatest in mustard, and least in oats and the legume/oats mix. The weed suppressive ability of each cover crop was affected by early-season canopy development and was highly correlated with cover crop plant density. Weed emergence following cover crop incorporation was in order of legume/oats mix > oats > mustard in yr 1, but was not different in yr 2. This study provides initial information on cover crop effects on weed management in irrigated and tilled vegetable production systems in the central coast of California. The results suggest that the legume/oats mix could exacerbate weed problems in subsequent vegetable crops.

Living Mulch as a Tool to Control Weeds in Agroecosystems: A Review

“…There is wide agreement in the literature that a vigorous living mulch will suppress weeds growing at the same time as the living mulch (Stivers-Young 1998; Akobundu et al 2000;Creamer and Baldwin 2000;Blackshaw et al 2001;Favero et al 2001;Grimmer and Masiunas 2004;Peachey et al 2004;Brennan and Smith 2005). In one study (Echtenkamp and Moomaw 1989), chewing fescue or red fescue (Festuca rubra L.) and ladino clover (Trifolium repens L.) were effective living mulches for controlling weed growth.…”

“…In another study, a live hairy vetch cover crop was more effective than a desiccated cover crop in suppressing weed emergence during the first four weeks and throughout the season (Teasdale et al 1991). In addition, if growth suppression is sufficient, a living mulch can inhibit weed seed production (Brainard and Bellinder 2004;Brennan and Smith 2005). Weed seed predation at the soil surface was also higher when living mulch vegetation was present (Davis and Liebman 2003;Gallandt et al 2005), suggesting a role for living mulches in enhancing weed seed mortality.…”

Response of leaf area and dry matter of crop, weeds and cover crops to competition and fertilizer resources

“…The suppressive effect of cover crop could be due to inhibition of weed seed germination through effect on the radiation and chemicals environment of seeds. Also continuous suppressive effect of cover crop could reduce seed production by weeds (Brennan and Smith, 2005).…”

Ação do extrato de Lolium multiflorum Lam. sobre atributos fisiológicos de sementes e plântulas de alface

“…A utilização de determinadas espécies como plantas de cobertura do solo pode ocasionar ambientes mais competitivos por água, luminosidade e nutrientes (Brennan & Smith 2005, Bergkvist et al 2010, Lawley et al 2012. A competição colabora para o desenvolvimento de mecanismos de defesa, baseados na síntese de metabólitos secundários (Rice 1984).…”