Safflower (Carthamus tinctorius L. ‘Hartman’) in the rosette growth stage or early bolting stage tolerated thiameturon {3-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] amino] sulfonyl]-2-thiophenecarboxylic acid} at 5, 10, and 15 g ai/ha. Safflower also tolerated chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} at 18 g/ha if safflower was taller than 15 cm at time of application. The fresh weight of above-ground biomass of common sunflower (Helianthus annuus L. #3 HELAN), treated at two plant sizes with thiameturon, was reduced more than 88%. Soil activity of thiameturon also reduced the seedling vigor of common sunflower, but thiameturon in soil was not as lethal to common sunflower as were foliar applications.

Under irrigated field conditions at Prosser, WA, Russian thistle [Salsola kali (L.) var. tenuifolia Tausch. ♯3 SASKR] began to emerge by mid-March each year and usually had completed its emergence by May 1. Common lambsquarters (Chenopodium album L. ♯ CHEAL) was the next to appear, usually during the third or fourth week of March. Barnyardgrass [Echinochloa crus-galli (L.) Beauv. ♯ ECHCG], redroot pigweed (Amaranthus retroflexus L. ♯ AMARE), hairy nightshade (Solarium sarrachoides Sendt. ♯ SOLSA), black nightshade (5. nigrum L. ♯ SOLNI), eastern black nightshade (S. ptycanthum Dun.), and cutleaf nightshade (S. triflorum Nutt. ♯ SOLTR) generally began to emerge during the first 2 weeks of April and emergence generally peaked mid-April to mid-May. Russian thistle and cutleaf nightshade had the most restricted emergence patterns, whereas seedlings of common lambsquarters, redroot pigweed, hairy nightshade, and black nightshade emerged each month from April through September. Shallow tillage at monthly intervals increased the overall emergence of common lambsquarters, redroot pigweed, black nightshade, and eastern black nightshade; decreased the emergence of barnyardgrass; and had no effect on the emergence of Russian thistle, cutleaf nightshade, or hairy nightshade.

Greenhouse and field studies were conducted to examine weed control with, and potato tolerance to, rimsulfuron or rimsulfuron + metribuzin applied POST. In greenhouse trials, hairy nightshade control with rimsulfuron applied POST at 9 to 35 g/ha was ≥ 90%, but cutleaf nightshade control was < 30%. In field studies, rimsulfuron at 18 to 35 g/ha provided ≥ 85% control of hairy nightshade, redroot pigweed, tumble pigweed, and shepherd's-purse; 75 to 82% control of volunteer oats; and 25 to 87% control of common lambsquarters. Common lambsquarters control was increased to 92 to 100% when rimsulfuron at 18 to 35 g/ha was applied in combination with metribuzin at 280 g/ha. Hairy nightshade and redroot pigweed control usually were not improved by adding metribuzin to the rimsulfuron spray mixture and tumble pigweed and shepherd's-purse control were improved only slightly. Volunteer oat control with rimsulfuron sometimes was antagonized by the addition of metribuzin to the spray mixture. In weed-free trials, yield of potatoes grown for the fresh market or to produce seed tubers was not reduced by rimsulfuron at rates as high as 70 g/ha.