Comparison of glufosinate-tolerant, glyphosate-tolerant, and non-transgenic cotton weed control systems
Two irrigated and two dryland studies were conducted in 2003 and 2004 to compare net returns between glufosinate- and glyphosate-tolerant, and conventional cotton weed management systems. Herbicides within each weed control system were sprayed as needed based on recommended label rates and limitations, and were made independent of the weed control inputs within other systems. Weed control system costs were calculated using seed costs including technology fees, herbicide and application costs, and mechanical inputs, and lint yields were determined. The net returns above weed control system costs in 2003 with the glyphosate-tolerant system was $1,514/ha in the Lubbock irrigated study, while the glufosinate-tolerant system and conventional system were $1,131 and $889/ha, respectively. The net returns above weed control system costs were similar and ranged from $780 to $854/ha in 2004. Net returns above weed control system costs were similar for all three systems when averaged over years at the Lubbock dryland location and in 2003 at a second dryland location near Lockett. The glufosinate- and glyphosate-tolerant systems had similar net returns when averaged over years at an irrigated study near New Deal, and were greater than the conventional system. Unlike the other three trials, the conventional weed control system generated greater net returns above weed control system costs at Lockett in 2004 compared to the glyphosate-tolerant system. The glyphosate-tolerant system generally required less input to maintain effective weed control compared to the glufosinate-tolerant system, while the glufosinate-tolerant system required less input compared to the conventional system.