The Biology of Invasive Alien Plants in Canada. 1. Eriochloa villosa (Thunb.) Kunth

The annual grass weed Eriochloa villosa, woolly cup grass, was reported for the first time in Canada in 2000, in southwestern Quebec. It is a serious agricultural pest of field crops in the Midwest United States where it has been difficult and expensive to control. The production of stolons early in the growing season and the extensive branching of stems later in the season mean that single plants occupy and disperse seed over a large area. Cleistogamous flowers ensure good seed set, and plants produce large numbers of seeds. After an initial spring germination flush, seeds continue to germinate throughout the growing season resulting in escapes from early control measures. The large seeds can germinate and emerge under a wide range of soil temperatures and soil depths. Woolly cup grass is tolerant of many herbicides and effective control in agro-ecosystems usually depends on integrated strategies of multiple herbicide applications, cultural and mechanical methods. The above biological features and its presence in a number of bordering States suggest that the species is a potential weed hazard in southern Canada, particularly in areas of corn and soybean production in Quebec and Ontario.