Absorption, Translocation, and Exudation of Glyphosate, Fosamine, and Amitrole in Field Horsetail (Equisetum arvense)

The absorption, translocation, and exudation of14C-glyphosate [N-(phosphonomethyl) glycine],14C-fosamine [ethyl hydrogen (aminocarbonyl)phosphonate] and14C-amitrole (3-amino-s-triazole) in field horsetail (Equisetum arvenseL.) were examined in glasshouse experiments. Amitrole was absorbed much more readily than either fosamine or glyphosate, and although the initial translocation of amitrole was faster, eventually more14C was recovered from the underground parts of plants treated with14C-glyphosate and fosamine. Radioactivity from all three compounds was translocated to areas of meristematic activity such as shoot and rhizome apices and rhizome nodes. The amounts of radioactivity recovered from the roots and rhizomes were small in relation to the amounts applied. Root exudation and guttation could account for some loss of herbicide from the plant. Radioactivity from14C-amitrole, in particular, was present in relatively large amounts in guttation fluid.