VIEW ARTICLE

Interactions between Alternaria porri and the Saprophytic Mycoflora of Onion Leaves. N. J. Fokkema, Postdoctoral Fellow, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca 14850, Present address of senior author: Phytopathologisch Laboratorium, "Willie Commelin Scholten", Baarn, The Netherlands; J. W. Lorbeer, Professor, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca 14850. Phytopathology 64:1128-1133. Accepted for publication 23 March 1974. DOI: 10.1094/Phyto-64-1128.

Infection of onion leaves by Alternaria porri was reduced by addition of Aureobasidium pullulans cells to the inoculum. Similarly, infection by Botrytis cinerea was reduced, while that by Botrytis squamosa was not. The common saprophytes of the onion phyllosphere, A. pullulans, Sporobolomyces roseus, Cryptococcus luteolus, and Cladosporium herbarum reduced infection of onion leaves by A. porri by 55%, 45%, –4%, and 18%, respectively. Superficial mycelial development of the pathogens rather than spore germination was affected by the antagonistic microorganisms. Suppression of infection appeared to be caused neither by depletion of carbohydrates and amino acids in the phyllosphere, nor by pH differences.