Efficacy of Reduced Sulfentrazone Rates Applied Preemergence with Metribuzin in Potato (Solanum tuberosum)1

Field trials were conducted with sulfentrazone at 53, 80, and 105 g ai/ha combined with 0, 420, and 560 g ai/ha metribuzin in a 3 by 3 factorial arrangement. Sulfentrazone and metribuzin combinations improved control of redroot pigweed, common lambsquarters, hairy nightshade, and volunteer oat compared with sulfentrazone applied alone. Kochia control was more than 90% regardless of metribuzin presence in the treatment. Sulfentrazone at 105 g/ha was needed for greater than 90% hairy nightshade control. Sulfentrazone alone or in combination with metribuzin did not provide greater than 89% volunteer oat control. Potato crop injury was less than 5% and total tuber yields increased as metribuzin rate increased from 0 to 560 g/ha, reflecting improved weed control as metribuzin rate increased.Nomenclature: Metribuzin; sulfentrazone; potato, Solanum tuberosum L. ‘Russet Burbank’; common lambsquarters, Chenopodium album L. #3CHEAL; hairy nightshade, Solanum sarrachoides Sendter # SOLSA; kochia, Kochia scoparia L. Shrad. # KCHSC; redroot pigweed, Amaranthus retroflexus L. # AMARE; volunteer oats, Avena sativa L. # AVESA.Additional index words: Crop safety, herbicide injury, reduced rates.Abbreviations: OM, organic matter; WAT, weeks after treatment.