Interactions of Fenoxaprop-ethyl with Fenchlorazole-ethyl in Annual Grasses
In growth room studies, POST applications of fenoxaprop-ethyl at 50 g ai ha−1 at the four- to five-leaf stage of development were non-toxic to barnyardgrass, large crabgrass, and yellow foxtail. POST applications of fenchlorazole-ethyl at 12.5 or 25.0 g ai ha−1 were also nontoxic to these same three species. However, when the two chemicals were applied in combination at the above rates they were toxic to all three species, indicating a synergistic interaction in all three species. In additional studies, a sensitive biotype of wild oat was severely injured by fenoxaprop-ethyl at 50 g ai ha−1 and a resistant biotype of wild oat was only slightly injured by fenoxaprop-ethyl at rates as high as 800 g ai ha−1. However, no significant interactions were observed between fenoxaprop-ethyl and fenchlorazole-ethyl in either of these wild oat biotypes.