Abstract
AbstractAdults of the sweetclover weevil, Sitona cylindricollis Fähr., injure seedling, vegetative, and yearling sweet clover, Melilotus officinalis (L.) Lam. In field cage tests an infestation of 1 weevil: 7 seedlings at the cotyledon stage destroyed less than 5%, and an infestation of 1 weevil: 1 seedling destroyed 100% of the seedlings. Significant reduction of seedlings was caused by infestations of I weevil: 3 or 5 seedlings depending upon growing conditions. An infestation of 4.5 to 9 weevils per emergent second-year plant caused a significant reduction, and an infestation of 18 weevils per plant caused almost total destruction of second-year forage yield. In the Canadian mid-west, weevil populations seldom exceed these minimum threshold values, therefore the weevil should not be considered a deterrent to either stand establishment or to stand retention in the second year. Defoliation of vegetative clover by weevils at the beginning of and mid-way through the critical period, which extends from 15 August to 20 September, caused a 50% loss of second-year forage yield. Because of cultural practices associated with sweet clover production in western Canada this may be the most severe type of injury wrought by the weevil.
Publisher
Cambridge University Press (CUP)
Subject
Insect Science,Molecular Biology,Physiology,Ecology, Evolution, Behavior and Systematics,Structural Biology
Cited by
8 articles.
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