BIOLOGY OF CANADIAN WEEDS.: 72. Apera spica-venti

Abstract

Apera spica-venti (silky bentgrass), a major weed of winter cereals in Europe for many years, has recently become established as a weed of winter cereals in three counties in southern Ontario. A review of the literature on the biology of the species is presented. Occurring on light sandy loam soils which are under a rotational tobacco/winter-cereal cropping system, infestations of silky bentgrass may result in considerable crop losses, particularly in winter-wheat. Several features contribute to the successful establishment and spread of the species: a winter annual habit concordant with the phenologies of winter cereals; numerous, light seeds easily dispersed by wind and farm machinery; production and early shedding of seed prior to the harvest of crops in July; little postharvest dormancy and the ability to germinate under a wide-range of temperature and light conditions. Although not yet registered for use in Canada, the herbicides isoproturon and chlortoluron would seem to provide effective control. Various cultural practices, including crop rotation, delayed seeding, and increased cultivation combined with the use of appropriate herbicides appear to be the ideal combination for control of silky bentgrass.Key words: Bentgrass (silky), weed biology, windgrass, loose silky bent