THE BIOLOGY OF CANADIAN WEEDS.: 90. Abutilon theophrasti

Abstract

Abutilon theophrasti Medic. (velvetleaf) forms extensive weed infestations in all major maize and soybean growing areas of Ontario and Quebec. A review of the literature on the biology of the species is presented. Velvetleaf causes crop losses through competition, allelopathic effects and by hosting insect pests and pathogens of crops. Velvetleaf has a number of features which contribute to its success as a weed, including: the production of a large number of seeds that have high viability with prolonged dormancy and sporadic, continuous germination patterns; robust seedling vigor; and the ability to produce seed under competition. Because of sporadic germination patterns, control is difficult. Effective control measures include the application of pre-emergence and/or postemergence herbicides followed by cultivation and additional herbicide applications to control escapes and later flushes of germination. A triazine-resistant bio-type of velvetleaf has recently been reported from the northeastern United States.Key words: Velvetleaf, Abutilon theophrasti, weed biology