Impact of black vine weevil,Otiorhynchus sulcatus (F.), on blackcurrants and strawberries in Canterbury

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Abstract
The black vine weevil, Otiorhynchus sulcatus (F.), was responsible for severe damage in blackcurrants (cv. ‘Magnus’) and strawberries (cv. ‘Tioga’) at Lincoln College in 1974. Larval root pruning of blackcurrants significantly reduced cane growth but had no significant effect on cane initiation. Strawberry plants in a black vine weevilinfested bed were separable into four damage classes based on visual assessment of leaf area: no damage, moderate damage, severe damage, and dead plants. Mean numbers of wcevil larvae per plant were 1.95, 8.35, 37.70, and 39.65 respectively. Comparisons of leaf area, number of leaves, and number of developing berries among the four damage classes showed that significant differences were detectable. Weevil larvae numbers per plant were significantly different among the first three classes but no difference was found between the severe-damage and dead-plant classes. Correlations between plant factors and weevil numbers within the first three damage classes were tested. Significant correlations in all three classes were found among the various plant factors, confirming relationships between leaf area, number of leaves, and number of developing berries. Only within the moderate-damage classes were significant correlations between number of weevils and the plant factors obtained. In strawberries economic loss will occur with between two to eight larvae per plant.