Toxicity and Translocation of Sethoxydim in Bermudagrass (Cynodon dactylon) as Affected by Environment

Toxicity and translocation of nonradiolabeled and translocation of 14 C-labeled sethoxydim {2-[1-(ethoxyimino)-butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexen-1-one} in common bermudagrass [ Cynodon dactylon (L.) Pers. ♯ 3 CYNDA] were evaluated for foliar treated plants grown 2 or 4 days under controlled environmental conditions. Nonradiolabel treated plants were further grown in the greenhouse for the remainder of 3 weeks. Shoot injury of intact plants was greatest (90%) and regrowth of plants clipped after 2 days treatment each was least (< 5%) at 35 C and 100% RH. At 35 C and 40% RH and at 18 C (40 and 100% RH), shoot injuries were 60 to 68%, regrowth in lengths were 82 to 87%, and in fresh weights were 55 to 74%, respectively. After 2 days treatment, absorption of 14 C-activity was greatest (70%) at 35 C and 100% RH, moderate (56%) at 35 C and 40% RH, and least (33 to 43%) at 18 C and 40 and 100% RH, respectively. At 35 C, translocation was approximately 4 fold greater at 100% and 2 fold greater at 40% RH than at 18 C at either RH. Autoradiography indicated the greatest distribution of the radiolabel at 35 C.