Performance interactions among HPPD-inhibiting and ALS-inhibiting herbicides for the control of annual grasses

Controlled environment and field experiments were conducted during 2006 and 2007 to evaluate performance interactions among HPPD-inhibiting and ALS-inhibiting herbicides for the control of annual grasses in corn. Nicosulfuron antagonized topramezone for the control of barnyard grass and large crabgrass in the controlled environment. These interactions were overcome with the addition of atrazine or an increase in the dose of nicosulfuron. Antagonistic interactions in the field were more pronounced in 2007 than in 2006. Tank-mixtures of topramezone plus nicosulfuron or nicosulfuron + rimsulfuron resulted in antagonistic interactions for the control of barnyard grass, and to a lesser extent giant green foxtail. Antagonism in the field was not influenced by growth stage of the annual grasses tested and it did not result in reduced yield. No antagonism was observed with tank-mixtures of topramezone plus foramsulfuron for the control of the annual grasses tested in both environments.