The Influence of the Apple Aphid/Spirea Aphid Complex on Intensity of Alternaria Blotch of Apple and Fruit Quality Characteristics and Yield. Nenad Filajdic, Former Graduate Research Assistant, Department of Plant Pathology; North Carolina State University, Raleigh 27695-7616. T. B. Sutton, Professor, Department of Plant Pathology, J. F. Walgenbach, Associate Professor, Department of Entomology, and C. R. Unrath, Professor, Department of Horticultural Science, North Carolina State University, Raleigh 27695-7616. Plant Dis. 79:691-694. Accepted for publication 27 February 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0691.

Two levels of aphid densities (apple aphid/spirea aphid complex) were established within treatments of two levels of Alternaria blotch at two locations in 1992 and one in 1993. At the high disease level, disease severity was greater in treatments in which a high aphid density was present. Defoliation was increased at one location in 1 year. Fruit quality characteristics such as soluble solids content, diameter, and weight were often decreased at the high aphid density; firmness was increased and commercial color decreased in some cases. Yield was not affected by aphids