Field studies were conducted in 2007 and 2008 near Nyssa, OR, and Pasco and Paterson, WA to evaluate yellow nutsedge and broadleaf weed control and potato tolerance to imazosulfuron. No injury symptoms from imazosulfuron were evident on potato at Nyssa, whereas in Washington, imazosulfuron caused some chlorosis of potato foliage ranging from 6 to 15% and < 4% at 6 and 15 d after POST application, respectively. Sequential applications of imazosulfuron controlled yellow nutsedge better than a single PRE application. Sequential applications of imazosulfuron or imazosulfuron in combination with s-metolachlor controlled yellow nutsedge > 92 and 89% at 21 and 42 d after POST applications, respectively. Imazosulfuron controlled ≥ 98% of common lambsquarters and 100% of pigweed species. Imazosulfuron provided season-long control of common mallow at Nyssa. However, imazosulfuron failed to control Russian thistle at Paterson, and only partially controlled hairy nightshade. Yield of U.S. no. 1 potato at Nyssa ranged from 44 to 54 T ha⁻¹ and 42 to 52 T ha⁻¹ for imazosulfuron PRE and imazosulfuron sequential treatments in 2007 and 2008, respectively. U.S. no. 1 potato yield following imazosulfuron PRE and sequential treatments at Pasco ranged from 49 to 57 T ha⁻¹ in 2007, and at Paterson from 36 to 54 T ha⁻¹ in 2008. Lower yields in 2008 were attributed to poor control of hairy nightshade. Imazosulfuron has potential to become a valuable tool for yellow nutsedge management in potato. Studies are needed to evaluate the soil persistence for imazosulfuron in order to determine safety to crops grown in rotation with potato.

Nomenclature: Imazosulfuron; rimsulfuron; s-metolachlor; common lambsquarters, Chenopodium album L.; common mallow, Malva neglecta Wallr.; hairy nightshade, Solanum physalifolium Rusby; pigweed, Amaranthus spp.; Russian thistle Salsola tragus L.; yellow nutsedge, Cyperus esculentus L. CYPES; potato, Solanum tuberosum L. ‘Russet Burbank’ and ‘Shepody’.