Research was conducted in 1996 and 1997 at the Horticulture Research Farm in Lexington, KY, to evaluate full season weed control and phytotoxicity for rates of sulfentrazone alone and in combination with Gallery (0.55 kg ai/ha) (0.49 lb ai/A), Treflan (2.18 kg ai/ha) (1.94 lb ai/A), and Pennant (3.27 kg ai/ha) (2.92 lb ai/A). In general, by 12 WAT, control provided by all treatments was only fair to moderate. The greatest reductions in weed cover were observed with the high rate of sulfentrazone (0.55 kg/ha) (0.49 lb ai/A), the combination of sulfentrazone (0.41 kg/ha) (0.37 lb ai/A) plus Pennant, and combinations of sulfentrazone plus Treflan. In all cases, weed control was improved with the use of a higher rate of sulfentrazone, and not necessarily associated with the presence of the partner herbicides. Phytotoxicity was mainly associated with contact of the herbicide with developing foliage, but sulfentrazone was particularly damaging to the herbaceous species Liriope and Hemerocallis, where damage was observed throughout the plants. Sulfentrazone was present in all cases where plants exhibited severe phytotoxicity in response to herbicide treatment. The most sensitive species evaluated in this study were: Abies, Liriope, and Hemerocallis. The most tolerant species included: Fraxinus, Crataegus, and Euonymus. Postemergence directed applications or shielded preemergence applications of sulfentrazone were recommended to possibly decrease phytotoxicity to sensitive species.

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Author notes

2Graduate Student.

3Extension Professor of Horticulture, University of Kentucky, Lexington KY 40546.

4Associate Professor of Horticulture, Cornell University, Ithaca, NY 14853. To whom all correspondences should be addressed.