Agronomy Library > Soil Conservation

Control of Winter Annuals in Reduced Tillage Systems
Author: Mirza N. Baig and Peter Gamache
Date Created: August 22, 2006
Last Reviewed: August 22, 2006

Winter annuals germinate in the fall, over-winter as low rosettes, resume their growth following spring, and flower and go to seed in late spring or early summer. In Alberta, the commonly occurring winter annuals are stinkweed, shepherd’s-purse, narrow-leaved hawk’s-beard, bluebur, flixweed, downy brome and common peppergrass. In some reduced tillage fields, during mild winters, some summer annuals can over-winter and exhibit winter annual habits. Some of the examples of this abnormal growth habit are cleavers, black medic, stork’s-bill, and night-flowering catchfly. Rosettes of winter annuals are strong competitors because of their rapid growth in the spring, and, if not controlled, they have the potential to cause serious yield losses in annual and perennial crops. 

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