Influence of herbicide application rate, timing, and interrow cultivation on weed control and corn (Zea mays) yield in glufosinate-resistant and glyphosate-resistant corn

Field trials were conducted in 1996 and 1997 to determine the influence of glufosinate and glyphosate application rates, application timings, and inte rrow cultivation on weed control and corn yield. Glufosinate-ammonium rates ranged from 0.18 to 0.41 kg ai/ha, while rates for the isopropylamine salt of glyphosate ranged from 0.21 to 0.84 kg ae/ha. Increasing rates of glufo sinate and glyphosate often improved weed control. Control of many of the w eed species was improved by delaying herbicide application timing. Weed con trol was most consistent from late postemergence (LPOST) applications of gl ufosinate at 0.41 kg ai/ha or glyphosate at 0.84 kg ae/ha. Corn yields were reduced due to incomplete weed control when the lowest rate of glufosinate was applied. Weed control from early postemergence (EPOST) glufosinate and glyphosate applications followed by cultivation was similar to weed contro l from LPOST glufosinate and glyphosate applications without cultivation. I nterrow cultivation following glufosinate or glyphosate application did not affect corn yield.