Cropping System Effects on Weed Emergence and Densities in Corn
2000
Singer, Jeremy W. | Cox, William J. | Hahn, Russell R. | Shields, Elson J.
The USDA has a goal of implementing integrated pest management (IPM) practices on 75% of the cropland in the USA so growers may adopt weed control practices that emphasize crop rotation and cultivation. Our objectives were to estimate weed densities in corn (Zea mays L.) and to examine weed emergence in an unmanaged weed area of corn following 4 yr of continuous corn, which received preemergence broadcast herbicides, and following soybean [Glycine max (L.) Merr.]–corn and soybean–wheat (Triticum aestivum L.)/red clover (Trifolium pratense L.)–corn cropping systems, which received banded herbicides and cultivation, on four farms in New York. More total weeds emerged at two sites and more perennial weeds emerged at all sites in the unmanaged weed area of corn in the soybean–wheat/red clover–corn cropping system compared with continuous corn because of poor red clover establishment, which resulted in a fallow period after wheat harvest. Weed densities in corn averaged 6.3 and 9.9 weeds m⁻² in the soybean–wheat/red clover–corn cropping system, compared with 1.7 and 1.0 weeds m⁻² in continuous corn at two of the sites, because of greater weed emergence and unsatisfactory weed control with banded herbicides and a single cultivation in the soybean–wheat/red clover–corn cropping system. When red clover does not establish well, growers should expect increased weed densities in the subsequent corn crop. Growers should then consider fall tillage or herbicide application after wheat harvest, or additional cultivation(s) or herbicide applications in the subsequent corn crop.
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