BROMOXYNIL ANTAGONIZES JOHNSONGRASS (SORGHUM-HALEPENSE) CONTROL WITH GRAMINICIDES

Field studies were conducted over 2 yr co evaluate rhizome johnsongras s control with tank mixtures and sequential applications of bromoxynil at 1.7 kg ai/ha and the graminicides clethodim, fluazifop-P, and quiz alofop-P. When compared with the graminicide alone, bromoxynil reduced johnsongrass control 28 days after treatment (DAT) 20, 36, and 55% wh en applied in combination with clethodim, fluazifop-P, and quizalofop- P. respectively. Application of bromoxynil 7, 3, and 1 d before or 1, 3, and 7 d after all graminicides reduced antagonism when compared wit h the bromoxynil plus graminicide mixtures. Based on johnsongrass cont rol 28 DAT, antagonism was precluded when bromoxynil was applied 3 d b efore clethodim and 7 d before fluazifop-P and quizalofop-P. Applicati on of bromoxynil 3 and 7 d after quizalofop-P and 7 d after clethodim also precluded antagonism, The antagonistic tank mixtures of bromoxyni l and graminicides reduced cotton yield 17% because of reduced johnson grass control compared with graminicides alone. A 3-d or greater appli cation interval between bromoxynil and the graminicides was necessary to maximize cotton yield.