VIEW ARTICLE

Ecology and Epidemiology

The Influence of Osmotic Water Potential on the Linear Growth of Endothia Species. Phil P. Hunter, Graduate Research Assistant, Department of Plant Pathology and Physiology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061; Gary J. Griffin(2), and R. Jay Stipes(3). (2)(3)Associate Professors, respectively, Department of Plant Pathology and Physiology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061. Phytopathology 66:1418-1421. Accepted for publication 3 May 1976. Copyright © 1976 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-66-1418.

The effect of osmotic water potential on the linear growth of Endothia gyrosa, E. parasitica, E. singularis, E. tropicalis, and Fusarium solani, together with reference fungi, was investigated. In general, all species of Endothia and F. solani exhibited decreasing growth with decreasing osmotic water potential. The growth of certain isolates was stimulated on KCl- and sucrose-adjusted media and inhibited slightly on NaCl- and salt mixture-adjusted media. The E. gyrosa isolates were able to grow at –60 bars in vitro. Observations of the changes in water potential in newly pruned branch stubs of pin oak (Quercus palustris) and the rate of ingress of E. gyrosa into such stubs showed that the fungus typically invaded the pruned stubs before water potentials reached –60 bars.