The major weedy biotypes of proso millet (Panicum miliaceum) in Canada

Abstract

Proso millet, Panicum miliaceum L., has become a problem weed in corn-growing areas of Canada over the last 15 years. Several different biotypes of this weed exist, and one of the features by which they may be distinguished from one another is seed colour. Those plants with dark olive – bronze – black seeds that shatter readily are the most difficult to control. Part of their success as weeds is due to their ability to form a long-term viable seed bank in the soil, making quick elimination from an area impossible. Other biotypes closely resemble crop types and have little dormancy or ability to form a long-term seed bank. Between these two extremes are 'crown' and some 'golden' biotypes, some populations of which have weedy characteristics that may make them more aggressive weeds as the selection process continues. Some biotypes are more readily controlled than others by a combination of management practices, including rotation and spraying. Good chemical control is available for use in some broad-leaved crops (e.g., soybeans), but consistently effective control of this weed in corn has not yet been achieved. Thus, a knowledge of the ecology of the weed can assist in other forms of management. Each biotype that has been discovered in Canada is described and illustrated, together with an outline of ecological characteristics that may aid in its identification and control.

The Biology of Canadian Weeds: 155.Panicum miliaceumL.

“…In crop-like weeds, described in Bough et al (1986), the seeds measure approximately 3.0 mm × 2.0 mm, whereas those of the black-seeded weed are slightly shorter and narrower (2.5-2.75 mm long and 1.5-1.75 mm wide). The husk varies in colour from light cream to olive-black and forms an integral part of the seed when it is shed.…”

“…The species encompasses both a wide range of crop types and several weedy biotypes (Bough et al 1986). …”

“…Several biotypes of P. miliaceum occur as weeds in Canada. Bough et al (1986) used these features to describe seven weedy biotypes of this species infesting fields in Manitoba, Ontario and Quebec. They based the names they ascribed to five of these biotypes on seed colour: White, Golden, Orange-red, Black and Dark red.…”

“…2 for drawings of the inflorescences of the Black, Golden, Crown and Dark red biotypes. In Quebec, Bouchard et al (1999) listed six biotypes based on seed colour [names used by Bough et al (1986) in brackets]; white, yellow (Golden), olive-green (Crown), orange (Orange-red), red-brown (Dark red) and dark green (Black). Dark green is the most invasive weed in that province.…”

Assessment of silver-stained AFLP markers for studying DNA polymorphism in proso millet (Panicum miliaceum L.)

“…This crop was first introduced into Canada in the 17 th century and in the last 25 years, wild-proso millet has become one of the most aggressive grass weed in North America (Bough et al 1986, Bough & Cavers 1987. High infestation by thos weed were first reported in Minnesota and Wisconsin in the early 1970s, and since this period, wild-proso millet has become a serious problem in different regions of the United States and Canada (Strand et al 1973, WSSA 1992.…”