Effects of tillage systems and weed management on weed populations in grain sorghum (Sorghum bicolor).

Field research was conducted from 1987 to 1991 to evaluate the influence of four weed management systems on weed population and species dynamics in conventional-tillage and no-tillage grain sorghum production. These weed management systems included zero, low, medium, and high input systems. The weed seedbank increased faster in zero and low input weed management systems than in the high input weed management systems because of differences in weed control. Tiliage influenced weed seed densities as well. Common ragweed, common lambsquarters, horseweed, and sicklepod seed densities often were greater in no-tiliage than conventional-tiliage plots. Common cocklebur and large crabgrass seed densities were usually greater in conventional-tiliage than no-tiliage plots. Smooth pigweed seed densities were not affected by tillage. Increasing weed management inputs diminished differences between tiliage systems. Smooth pigweed dominated the weed populations after 4 yr in both tillage systems even in high input systems. Nomenclature: Common lambsquarters, Chenopodium album L. #3 CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMIBEL; common cocklebur, Xanthium strumarium L. #XANST; large crabgrass,Digitaria sanguinalis (L.) Scop. # DIGSA; smooth pigweed, Amaranthus hybridus L. # AMACH; grain sorghum, Sorghum bicolor (L.) Moench. 'Pioneer 8333.' Additional index words: Conservation-tillage, weed seedbank, AMBEL, CASOB, CHEAL, DIGSA, ERICA, XANST.