Differential Absorption and Distribution as a Basis for the Selectivity of Bifenox

Abstract

The uptake and distribution of14C-bifenox [methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate] was different among corn(Zea maysL.), soybean(Glycine max(L.) Merr.) and velvetleaf(Abutilon theophrastiMedic.) following preemergence application to a greenhouse soil mix. Autoradiographs of seedlings harvested 14 days after treatment, showed the14C to be in (or on) those areas of the crop plant in contact with the treated soil. Velvetleaf translocated14C residue throughout the shoot. Absorption of14C-compound(s) from treated nutrient solution accumulated in the roots of the three species but to a greater extent in soybean. There was no difference in the concentration of14C in the shoots. However, in corn and soybean the14C-compound(s) was confined to the primary and secondary leaf veins while velvetleaf showed a general distribution throughout the leaf tissue. Velvetleaf absorbed and translocated bifenox from shoot zones to a greater extent than the crop plants. Some acropetal movement was noted following leaf application to corn and velvetleaf but movement was only 3% of applied14C from the treated leaf. No movement was detected in soybean.