SCENTLESS CHAMOMILE (MATRICARIA-PERFORATA) GROWTH, DEVELOPMENT, AND SEED PRODUCTION

Field experiments were conducted to determine the growth, development, and seed yield response of scentless chamomile when planted at variou s dates throughout the growing season. Scentless chamomile emerged wit hin 6 to 15 d of planting and required 75 to 131 growing degree days ( GDD). Flowering occurred within 56 to 82 d of planting and required 58 4 to 845 GDD. Plants that emerged in mid-July and onward did not flowe r in that season but survived as winter annuals. Spring-planted scentl ess chamomile matured within 97 to 127 d and required 906 to 1,176 GDD . Plants that emerged in May and June attained more leaf area and biom ass than plants that emerged in mid-summer. Plants that emerged early in the growing season produced three-to fourfold more seed than plants that emerged at later dates. Scentless chamomile seed production rang ed from 71,000 to 256,000 plants(-1) depending on planting date and ex isting environmental conditions. Results are discussed in terms of its potential to become an increasingly troublesome weed in crops of the Canadian prairies and possible management strategies for its control.