来源： Zouhar, 2001
Probably introduced to North America in the 1600s as a contaminant of crop seed and/or ship's ballast.
Canada thistle is listed as a noxious weed in 7 Canadian provinces.
农业: Zouhar (2001) states that it is considered one of the most tenacious and economically important agricultural weeds. Nuzzo (2001) states that infestations reduce crop yield through competition for water, nutrients and minerals, and through interference with harvest. In Canada, the major impact is on agricultural land and in natural areas that have been disturbed or are undergoing restoration.
最后修改 ： 15/02/2004 4:11:04 p.m.