Fate of Fluorodifen in Susceptible Cucumber Seedlings

Abstract

Rapid absorption and acropetal translocation of¹⁴C fromp-nitrophenyl-α,α,α-trifluoro-2-nitro-p-tolyl ether (fluorodifen) labeled with¹⁴C at either the 1 position of thep-nitrophenyl ring (fluorodifen-1′-¹⁴C) or the trifluoromethyl carbon (fluorodifen-¹⁴CF₃) were observed in cucumber(Cucumis sativusL. ‘Ashley’) seedlings after root treatment via nutrient solution. The major degradative products of fluorodifen-1′-¹⁴C werep-nitrophenol and Unknown I (possibly a conjugate ofp-nitrophenol). Somep-nitrophenyl-α,α,α-trifluoro-2-amino-p-tolyl ether (2-amino-fluorodifen),p-aminophenyl-α,α,α-trifluoro-2-amino-p-tolyl ether (p,2-diamino-fluorodifen),p-aminophenyl-α,α,α-trifluoro-2-nitro-p-tolyl ether (p-amino-fluorodifen), and several minor unknowns also were detected. The major degradative product of fluorodifen⁻¹⁴CF₃was Unknown II (possibly a conjugate of 2-amino-4-trifluoromethylphenol). Also detected were some 2-amino-fluorodifen, 2-amino-4-trifluoromethylphenol,p-amino-fluorodifen,p2-diamino-fluorodifen, 2-nitro-4-trifluoromethylphenol, and several minor unknowns. The basic difference in susceptibility to fluorodifen of cucumber and peanut(Arachis hypogaeaL. ‘Starr’) appears to be due to the rate of acropetal translocation (cucumber translocates more than peanut) and the rate of degradation (peanut degrades fluorodifen much more rapidly than cucumber).