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Ecology and Epidemiology

The Influence of Fungi Isolated from Peach Twigs on the Pathogenicity of Cytospora cincta. D. J. Royse, Graduate Research Assistant, Department of Plant Pathology, University of Illinois, Urbana, IL 61801, Present address of senior author: Department of Plant Pathology, Pennsylvania State University, University Park, PA 16802; S. M. Ries, Assistant Professor, Department of Plant Pathology, University of Illinois, Urbana, IL 61801. Phytopathology 68:603-607. Accepted for publication 3 October 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-603.

Four species of fungi consistently isolated from twig elements (bud, leaf scars, and internodes) of peach (Prunus persica ‘Redhaven’) were studied in combination with Cytospora cincta, causal agent of perennial peach canker. Alternaria alternata, Epicoccum purpurascens, and Coniothyrium olivaceum when grown on potato-dextrose agar (PDA) produced substances or caused nutrient depletion which adversely affected the germination and germ-tube growth from conidia of C. cincta. In contrast, Aureobasidium pullulans produced diffusible products on PDA that stimulated germ-tube growth from C. cincta conidia. Epicoccum purpurascens produced the largest zones of inhibition when grown in dual culture with C. cincta and produced at least two antifungal compounds inhibitory to conidial germination of C. cincta. Epicoccum purpurascens, C. olivaceum, and A. alternata wound-inoculated singly or in various combinations with C. cincta, inhibited canker development on peach twigs. Epicoccum purpurascens and C. olivaceum were most effective in reducing disease severity when inoculated with C. cincta in the field, whereas A. pullulans did not significantly (P = 0.05) reduce canker enlargement.