Glyphosate for Orobanche aegyptiaca control in Vicia sativa and Brassica napus

Use of glyphosate in controlling Orobanche aegyptiaca (broomrape), a parasitic weed on dicotyledonous crops, was examined by determining glyphosate dose response and 14C-labeled glyphosate absorption, translocation, and metabolism patterns in Vicia sativa (common vetch) that is tolerant of low levels of glyphosate and Brassica napus (oilseed rape) that has been genetically engineered to be glyphosate resistant. Glyphosate provided excellent suppression of O. aegyptiaca growth in both V. sativa and B. napus. Absorption and translocation of 14C-glyphosate was similar between parasitized and nonparasitized V. sativa plants. 14C-Glyphosate was metabolized up to 32% in V. sativa, which could account for some of the tolerance of V. sativa to glyphosate. Approximately 27% of translocated 14C-glyphosate accumulated in O. aegyptiaca attachments on V. sativa. Absorption and translocation patterns of 14C-glyphosate were similar between parasitized and nonparasitized B. napus plants. Nearly one-third (31%) of the translocated radioactivity was found in O. aegyptiaca attachments on B. napus. No metabolism of 14C-glyphosate was detected in B. napus.