Published online by Cambridge University Press: 20 January 2017
Field experiments were conducted in 2000 and 2001 near Painter, VA, to evaluate the potential of sulfentrazone for use in potato. Sulfentrazone was applied at 0.11, 0.14, 0.21, and 0.28 kg ai/ha preemergence (PRE) alone or in combination with metolachlor or metribuzin, or at emergence (AT EMERG) of potato to simulate a delayed PRE application where the herbicide would come into contact with potato foliage. Potato injury from sulfentrazone PRE at rates of up to 0.21 kg/ha was generally similar to injury from metribuzin, metolachlor, or metribuzin plus metolachlor PRE. However, AT EMERG applications resulted in excessive injury that ranged from 60 to 86%. AT EMERG applications also caused decreased potato height and alterations in potato-flowering patterns. Sulfentrazone at either application timing controlled common lambsquarters at least 98% even at the lowest rates and was more effective than metribuzin or metolachlor alone. Higher rates of sulfentrazone (0.28 kg/ha) also controlled goosegrass and large crabgrass. However, sulfentrazone at 0.28 kg/ha controlled common ragweed only 58%. Total potato yield and grade with sulfentrazone PRE applications were similar to those of potato treated with metribuzin, metolachlor, or metribuzin plus metolachlor in both years. Potato injury from AT EMERG applications of sulfentrazone plus metolachlor decreased total potato yield and caused changes in the grade distribution of B-size, small A–size, and extra-large potato in 2000.