Abstract: The experimental sulfonylurea herbicide ASC-67040 was evaluated preemergence (PRE) and postemergence (POST) at 25 to 100 g ai/ha and PRE at 50 g/ha followed by ASC-67040 POST at 50 g/ha for broadleaf weed control in potato and tomato. In Virginia, ASC-67040 POST at 50 and 100 g/ha gave 70 to 98% control of common lambsquarters, common ragweed, and jimsonweed with slight (0 to 6%) ‘Superior’ potato and moderate (0 to 23%) ‘Agriset’ tomato injury. This crop injury was present primarily as chlorosis in terminal growth and disappeared by 3 wk after treatment (WAT). Potato tuber and tomato fruit yields were high in ASC-67040-treated plots. In North Carolina, ASC-67040 PRE and POST at 50 and 100 g/ha controlled 10 species of annual broadleaf weeds and grasses, and at 25 g/ha ASC-67040 gave greater than 90% control of most species. ASC-67040 injured ‘Fontenot’ potato more than Superior and caused 10 to 13% injury to ‘Mountain Spring’ tomato but did not injure ‘Mountain Pride’ tomato. Mountain Spring tomato recovered rapidly and produced high yields. In the greenhouse, yellow nutsedge control by ASC-67040 POST at 25 to 100 g/ha was 59 to 86% 3 WAT and yellow nutsedge height, dry weight, and regrowth dry weight were reduced by all rates. Lower rates of ASC-67040 might control weeds and cause less injury to potato and tomato.
Nomenclature: ASC-67040 (proposed name fluazasulfuron), 1-(4,6-dimethoxypyrimidin-2-yl)-3-[3-trifluoromethyl-pyridin-2-yl)sulfonyl]urea; metolachlor; metribuzin; trifluralin; common lambsquarters, Chenopodium album L. #3 CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; jimsonweed, Datura stramonium L. # DATST; yellow nutsedge, Cyperus esulentus L. # CYPES; potato, Solanum tuberosum L. ‘Fontenot’, ‘Superior’; tomato, Lycopersicum esculentus L. ‘Agriset’, ‘Mountain Pride’, ‘Mountain Spring’.
Additional index words: Metolachlor, metribuzin, trifluralin, Ambrosia artemisiifolia, Cyperus esculentus, Datura stramonium, AMBEL, CHEAL, CYPES, DATST.
Abbreviations: ALS, acetolactate synthase (EC 4.1.3.18); DAP, days after planting; DATP, days after transplanting; DAT, days after treatment; fb, followed by; POST, postemergence; PPI, preplant incorporated; PRE, preemergence in potato and pretransplant surface applied in tomato; WAT, weeks after treatment.
