EVIDENCE OF CONTAMINATION OF PEDIGREED CANOLA (BRASSICA NAPUS) SEEDLOTS IN WESTERN CANADA WITH GENETICALLY ENGINEERED HERBICIDE RESISTANCE TRAITS

The objective of this study was to survey pedigreed canola (Brassica napus L.) seedlots for contaminating herbicide resistance traits because of complaints from farmers regarding glyphosate [N‐(phosphonomethyl)glycine]‐resistant canola volunteers occurring unexpectedly in their fields at densities and in patterns that suggested that pollen‐mediated gene flow from neighboring fields in previous years was not the source of contamination. Twenty‐seven unique, commercial certified canola seedlot samples were collected. Glyphosate‐resistant seedlot samples were not collected. Canola samples were planted in the field, and when the canola had two to four true leaves, glyphosate, glufosinate [2‐amino‐4‐(hydroxymethylphosphinyl)butanoic acid], and thifensulfuron {methyl 3‐[[[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)amino]carbonyl]amino]sulfonyl]‐2‐thiophenecarboxylate} herbicides were applied. Surviving canola plants were counted. Of the 27 seedlots, 14 had contamination levels above 0.25% and therefore failed the 99.75% cultivar purity guideline for certified canola seed. Three seedlots had glyphosate resistance contamination levels in excess of 2.0%. Unexpected contamination (even at 0.25%) can cause problems for producers that practice direct seeding and depend on glyphosate for nonselective, broad‐spectrum weed control. To avoid unexpected problems and costs, it is important that farmers are cognizant of the high probability that pedigreed canola seedlots are cross‐contaminated with the various herbicide resistance traits.