The absorption, translocation, and exudation of 14C-glyphosate [N-(phosphonomethyl) glycine], 14C-fosamine [ethyl hydrogen (aminocarbonyl)phosphonate] and 14C-amitrole (3-amino-s-triazole) in field horsetail (Equisetum arvense L.) 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 more 14C was recovered from the underground parts of plants treated with 14C-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 from 14C-amitrole, in particular, was present in relatively large amounts in guttation fluid.
