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 levels of herbicides and rotary hoeing were evaluated in combination with interrow cultivation for weed control in corn (Zea mays L.) planted into chisel-plowed or untilled seedbeds, Atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] at 1.1 kg a,i. ha(-1) or cyanazine {2-[[4-chloro-6(ethylamino)-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 compared with no herbicide use. These reduced herbicide treatments often controlled weeds as well as a standard full-rate treatment (atrazine at 1.6 kg ha(-1) plus 2.0 kg a.i, ha(-1) metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide]) prior to cultivation in both tillage systems. In the chisel-plow experiment, rotary hoeing was not as effective as atrazine or cyanazine in reducing early-season weed growth, In most cases, one or two interrow cultivations following atrazine or cyanazine increased weed control and corn grain yield to levels 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 corn planted in conservation tillage systems.