Fate of Fluorodifen in Resistant Peanut Seedlings

Rapid absorption and limited acropetal movement of 14C from p-nitrophenyl-α,α,α-trifluoro-2-nitro-p-tolyl ether (hereafter referred to as fluorodifen) labeled with 14C at either the 1 position of the p-nitrophenyl ring (fluorodifen-1′-14C) or the trifluoromethyl carbon (fluorodifen-14CF3) were observed in peanut (Arachis hypogaea L., var. Starr) seedlings after root treatment for 48 hr followed by 96 hr in nutrient solution. Major products of degradation of fluorodifen-1′-14C were p-nitrophenol and Unknown I (possibly a conjugate of p-nitrophenol). Some p-nitrophenyl-α,α,α-trifluoro-2-amino-p-tolyl ether and several minor unknowns were detected. The major product of degradation of fluorodifen-14CF3 was Unknown II (possibly a conjugate of 2-amino-4-trifluoromethylphenol). Some 2-amino-4-trifluoromethylphenol and traces of p-nitrophenyl-α,α,α-trifluoro-2-amino-p-tolyl ether, p-aminophenyl-α,α,α-trifluoro-2-nitro-p-tolyl ether, p-aminophenyl-α,α,α-trifluoro-2-amino-p-tolyl ether, and several minor unknowns also were detected. A major pathway of fluorodifen degradation in peanut seedlings is postulated whereby fluorodifen is reduced to the 2-amino derivative which is cleaved at the ether linkage to yield p-nitrophenol and 2-amino-4-trifluoromethylphenol. The respective phenols are then conjugated with natural plant substances to form water soluble conjugates.