INTEGRATING MECHANICAL WEEDING WITH REDUCED HERBICIDE USE IN CONSERVATION TILLAGE CORN PRODUCTION SYSTEMS

Integrated weed management for conservation tillage systems is needed so producers can minimize the environmental impacts of crop production while maintaining effective weed control and profitability, Reduced l evels of herbicides and rotary hoeing were evaluated in combination wi th interrow cultivation for weed control in corn (Zea mays L.) planted into chisel-plowed or untilled seedbeds, Atrazine hyl-N'-(1-methyleth yl)-1,3,5-triazine-2,4-diamine] at 1.1 kg a,i. ha(-1) or cyanazine -1, 3,5-triazin-2-yl]amino]-2-methylpropanenitrile) at 1.7 kg a.i. ha(-1) applied within 2 d after corn planting greatly reduced weed growth com pared with no herbicide use. These reduced herbicide treatments often controlled weeds as well as a standard full-rate treatment (atrazine a t 1.6 kg ha(-1) plus 2.0 kg a.i, ha(-1) metolachlor -ethyl-6-methylphe nyl)-N-(2-methoxy-1-methylethyl) acetamide]) prior to cultivation in b oth tillage systems. In the chisel-plow experiment, rotary hoeing was not as effective as atrazine or cyanazine in reducing early-season wee d growth, In most cases, one or two interrow cultivations following at razine or cyanazine increased weed control and corn grain yield to lev els similar to the full-rate treatment in both the chisel-plow and no- tillage systems, Integrating interrow cultivation with reduced levels of herbicide maintained weed control and corn yield compared with the full-rate treatment and is an effective weed management option for cor n planted in conservation tillage systems.