Journal or Publishing Institution: Expert Committee on Weeds
Author(s): Topinka, K., Hoffman, J., and Hall, L.
Article Type: Peer Reviewed Study
Record ID: 2001
Abstract: A field in which Brassica napus volunteers were not controlled by several applications of glyphosate was investigated in 1998. This field had been planted with glufosinate-resistant and imidazolinone-resistant B. napus in 1997 and was adjacent to a field that had grown glyphosate-resistant B. napus. Mature volunteer B. napus were collected on a 50- by 100-m grid in the field. Progeny from 34 volunteers were sprayed with glyphosate at 440 g ae ha−1, and the survivors were sprayed with either glufosinate or imazethapyr at 400 or 50 g ai ha−1, respectively. Where seed numbers permitted (14 volunteers), seedlings were also sprayed sequentially with glyphosate, glufosinate, and imazethapyr, at 440 g ae ha−1, 400 g ai ha−1, and 50 g ai ha−1, respectively. In total, 15 volunteers had progeny that were between 66 and 82% resistant to glyphosate, consistent with the predicted 3:1 resistant : susceptible ratio. Volunteer B. napus plants with glyphosate-resistant seedlings were most common close to the putative pollen source; however, a plant with glyphosate-resistant progeny was collected 500 m from the adjacent field edge. Seedlings from all nine volunteers collected from the glufosinate-resistant area showed multiple resistance to glyphosate and glufosinate, whereas seedlings from 10 of 20 volunteers collected from the imidazolinone-resistant area showed resistance to imazethapyr and glyphosate. DNA extraction and restriction fragment length polymorphism (RFLP) analysis of seedlings confirmed that mature B. napus volunteers were hybrids resulting from pollen transfer rather than inadvertent seed movement between fields. Two seedlings from the 924 screened were resistant to all three herbicides. Progeny from these self-pollinated individuals were resistant to glyphosate and glufosinate at the predicted 3:1 resistant : susceptible ratio and resistant to imazethapyr at the predicted 15:1 resistant : susceptible ratio. Sequential crossing of three herbicide-resistant varieties is the most likely explanation for the observed multiple herbicide resistance. Integrated management techniques, including suitable crop and herbicide rotations, herbicide mixtures, and nonchemical controls should be used to reduce the incidence and negative effect of B. napusvolunteers with multiple herbicide resistance.
Keywords: Brassica napus L., oil-seed rape ALS, acetolactate synthase EPSP, enolpyruvylshikimate-3-phosphate, Pollen transfer, herbicide, tolerance, volunteer, canola, oilseed rape; pollen, pollen flow, hybrids, volunteers, crossing, weed science, restriction fragment length polymorphism, edge effects, DNA, progeny, planting, glufosinate, imazethapyr, herbicide resistance, self-pollination, seedlings, glyphosate; Volunteerism, Seeds, Herbicides, Transgenes, Hybrid species, Oilseeds, Enzymes, Brassica napus, Brassica napus var. oleifera, Brassicales, plants, crop plants as weeds, cross resistance, crosses, glufosinate-P, herbicide resistant weeds, pollen flows, swede rape, volunteer plants, weeds, Capparales, phosphinothricin, weedicides, weedkillers, Alberta, Canada
Citation: Topinka, K., Hoffman, J., and Hall, L., 1999. Pollen flow between herbicide tolerant canola (Brassica napus) is the cause of multiple resistant canola volunteers. Expert Committee on Weeds (ECW), Ottawa.