EFFECTIVENESS OF NICOSULFURON AND PRIMISULFURON ON WIRESTEM MUHLY (MUHLENBERGIA-FRONDOSA) IN NO-TILL CORN (ZEA-MAYS)

Field experiments were conducted in 1992 and 1993 to evaluate wirestem muhly control in no-till corn with application of glyphosate, nicosul furon, and primisulfuron. Glyphosate was applied preplant at 1.1 kg ai /ha. Nicosulfuron and primisulfuron were applied at 0.018, 0.036, and 0.072 kg ai/ha and 0.020, 0.040, and 0.080 kg ai/ha, respectively, at four postemergence timings that included a split application. Similar experiments were conducted with wirestem muhly grown from rhizomes and seed in the greenhouse. Glyphosate was the most effective herbicide i n the greenhouse, providing at least 96% control. However, preplant ap plication of glyphosate in the field was ineffective in controlling wi restem muhly. On average, nicosulfuron and primisulfuron never exceede d 72% control of wirestem muhly in the greenhouse or in the field. Nic osulfuron was generally more effective than primisulfuron. Control wit h split application timings was more uniform over a 12-wk period than single applications and late postemergence applications were often too slow acting to affect wirestem muhly growth. Although neither nicosul furon nor primisulfuron controls wirestem muhly, both can provide supp ression of this weed where other alternatives do not exist.