Cover crops during winter fallow as a weed management strategy in maize hybrid seed production

ALONSO, JUAN I; DE LA FUENTE, ELBA B; POGGIO, SANTIAGO L; JÁNDULA, TOMÁS

Vancouver

Congreso; 5th International Weed Science Congress; 2008

International Weed Science Society

Maize hybrid seed production use high levels of inputs (irrigation, fertilisers and agrochemicals) to maximise seed yield. However, weed growth is usually greater than in grain maize crops because of both high resource availability and low crop cover, the latter due to spatial arrangement and small size of maize plants. This cropping system usually requires additional herbicide applications to control weeds. Thus, including cover crops in maize hybrid seed production may help to manage weeds in a sustainable way, through both preventing seed germination and suppressing plant growth. Our aim was to study how legume and grass cover crops affect weed communities during the fallow period and the following maize hybrid seed crop. Field experiments were carried out in two locations of the central Rolling Pampa (Argentina) in two consecutive years, during the winter fallow period between soybean and maize hybrid seed crops. First year experiments included two control treatments with and without glyphosate application, and cover crops of Italian ryegrass (Lolium multiflorum) and Persian clover (Trifolium resupinatum), whereas the second year experiments also included ryegrass-clover mixture. Floristic composition, ground-cover and biomass of weeds were evaluated. Ground-cover and biomass of ryegrass, clover and maize seed yield were measured. Ryegrass cover crop has the highest suppressive effect on weed growth due to its high biomass production. Common chickweed (Stellaria media) was the most frequent winter weed, being importantly suppressed by cover crops, particularly in those cover crops with high biomass of ryegrass. Maize seed yield was not affected by the previous treatments. Large crabgrass (Digitaria sanguinalis) and crested anoda (Anoda cristata) were the most frequent weeds in maize. Crested anoda was suppressed by cover crops, whereas herbicide applications during fallow appear to be more effective to reduce large crabgrass growth. Cover crops may contribute to sustainable weed management in hybrid seed production of maize, without affecting maize yield and economical results in a short term. Moreover, cover crops may help to maintain soil chemical and physical properties in a long term.