Notes on Limitations of Natural Control of Phytophagous Insects and Mites in a British Columbia Orchard

Abstract

When an apple orchard is abandoned in Eastern Canada the trees may continue to grow reasonably well for many years. As a rule the fruit is ruined by apple scab, but damage from insects or mites may be relatively minor. Under such conditions, phytophagous insects and mites are commonly held to an acceptable commercial level by natural control factors. On the other hand, when an apple orchard is abandoned in the semi-arid, southern interior of British Columbia the trees generally die from desiccation in a short time. Occasionally, when particularly favoured by sub-irrigation, they may survive for ten years or more. But they produce no marketable fruit; invariably it is ruined by insects. Unlike the abandoned eastern orchard. that in British Columbia his little natural protection from the codling moth, Carpocapsa pomonella (L.), and the blister mite, Eriophyes pyri (Pgst.), to mention but two common pests.