Flax tolerance to thifensulfuron and tribenuron

Abstract

Field experiments were conducted in 1994 and 1995 at Morden, Manitoba to investigate the tolerance of NorLin flax and FP 967, a sulfonylurea-resistant flax cultivar, to thifensulfuron and tribenuron. Herbicides were foliarly applied at 0, 1.3, 3.8, 7.5, 15, and 30 g ai ha−1. Thifensulfuron caused chlorosis, stunting, delayed flowering and maturity in NorLin, but yields were unaffected. Tribenuron severely injured NorLin flax and reduced seed yields at doses as low as 1.3 g ha−1. FP 967 exhibited good tolerance to foliar applications of thifensulfuron, but was injured by higher doses of tribenuron. This suggests that FP 967 is not completely cross-resistant to all sulfonylurea herbicides. Key words: Sulfonylurea, transgenic flax, crop tolerance, dose response, yield, oil content