An apple orchard, planted in 1986, was studied to evaluate the effect of rootfeeding (edaphic) woolly apple aphids, Eriosoma lanigerum (Hausmann), on tree growth and productivity. Tree trunk diameter and branch linear growth were measured yearly from 1989 to 1992; fruit weight, number of fruit, fruit drop, and fruit set for 1991 and 1992 were regressed against the number of aphid colonies on roots and a root infestation rating. Linear growth was significantly reduced by edaphic woolly apple aphids in 1989 and 1991. In 1991, with low fruit production, yield was unaffected by edaphic woolly apple aphids. In 1992, with high fruit production, there was a significant reduction in the number of fruit and weight of fruit per tree by the number of root colonies, partly because of increased fruit drop and reduced fruit set. Average yield loss was 2.4 kg (5.28 pounds) or 13 apples per tree. Based on a typical packout and actual prices for 1992, the gross loss was $465.18/ha ($188.25/acre). Woolly apple aphids were on only 11.5% of terminals and wounds in this orchard. Reduction in amount of storage carbohydrates in galled roots is a partial explanation of how this aphid reduces tree growth and production.
Document Type: Research Article
Publication date: February 1, 1995
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.