SWEET-POTATO (IPOMOEA-BATATAS) CLONES DIFFER IN RESPONSE TO ETHYL-METRIBUZIN

Six commercial sweet potato clones were evaluated in field and greenho use studies for the ethylthio analog of metribuzin (ethyl-metribuzin) tolerance. 'Southern Delite' was most tolerant in field studies and 'C ordner' the most tolerant in the greenhouse. 'White Delite' was the mo st susceptible clone in the field and greenhouse. Considering the rate s used in this study, all the sweet potato clones generally were toler ant to ethyl-metribuzin. When averaged over all clones, sweet potato i njury increased as the ethyl-metribuzin rate increased from 1.6 to 3.2 kg/ha but injury decreased as the season progressed and was minimal i n late season, Ethyl-metribuzin did not reduce marketable yields at Cl ayton, NC. At Clinton, NCI ethiozin PRE, POST, or PRE followed by POST at 3,2 kg/ha or PRE at 1.6 kg/ha reduced yield.