The biology of Canadian weeds. 8. Sinapis arvensis L. (updated)

An updated review of biological information is provided for Sinapis arvensi s L. Native to the Old World, the species is widely introduced and naturali zed in temperate regions around the world. The species occurs in all the pr ovinces, the Northwest Territories, and the Yukon. It is an important weed of field crops in the Canadian prairies. A strongly persistent seedbank, co mpetitive annual growth habit and high fecundity all contribute to its weed y nature and ensure that it will be a continuing problem. Several cases of herbicide resistance have been documented for natural populations of S. arv ensis in Canada, including biotypes resistant to: i) Group 2 herbicides, wh ich inhibit acetolactate synthase (ALS), from Manitoba in 1992 and Alberta in 1993; ii) Group 4 herbicides or synthetic auxins from Manitoba in 1991; and nl) Group 5 herbicides, which inhibit photosynthesis at photosystem II, from Ontario in 1983. The species is a close relative of Brassica nigra (L .) Koch, black mustard, and is capable of limited genetic exchange with the Brassica crop species under laboratory hybridization conditions either by conventional crossing or with the aid of ovary/embryo recovery techniques.