Broadleaf Weed Control in Potatoes (Solanum tuberosum) with Postemergence Directed Herbicides

Field studies were conducted to evaluate potato injury and weed control with postemergence-directed (PDIR) bromoxynil, glufosinate, or monocarbamide dihydrogen sulfate (MCDS). All three herbicides controlled hairy nightshade, common lambsquarters, redroot pigweed, and kochia ≥ 85%, depending on rate, with either mid- or late-PDIR treatment. Bromoxynil or MCDS caused 5 to 6% more initial injury with mid- than with late-PDIR treatment, but total yield and yield of U.S. #1 tubers were not reduced by either herbicide. PDIR glufosinate caused moderate injury at 0.84 kg ha−1, the rate needed for acceptable (≥ 85%) weed control. Total yield was reduced 10% and U.S. #1 yield was reduced 30% by PDIR glufosinate at 0.84 kg ha−1. Thus bromoxynil and MCDS showed potential for use as PDIR treatments in potatoes, but glufosinate did not.