Absorption, Action, and Translocation of Glyphosate

Abstract

Radioactive glyphosate [N-(phosphonomethyl)glycine] is rapidly absorbed with a large portion of the 14C translocated to the rhizomes and untreated shoots of quackgrass [Agropyron repens (L.) Beauv.]. The adjuvant used with glyphosate was important in determining its phytotoxicity to quackgrass. In other perennial weeds and annual species, glyphosate also moved to the areas of highest metabolic activity. In Canada thistle [Cirsium arvense (L.) Scop.], bentazon (3-isopropyl-1H-2,1,3-benzothiadiazin-(4) 3H-one 2,2-dioxide) at 2.24 kg/ha applied prior to treatment with 14C-glyphosate reduced 14C translocation. Iron or nitrilotriacetic acid (NTA) did not appear to effect glyphosate activity on wheat (Triticium aestivum L. ‘Avon’). The respiration of quackgrass treated with glyphosate was significantly reduced 9 days after treatment. Glyphosate reduced total photosynthesis more in quackgrass than in wheat.