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Physiology and Biochemistry

Stomatal Resistance of Red Oak Seedlings Infected by Ceratocystis fagacearum. D. O. TeBeest, Research Assistant, Department of Plant Pathology, University of Wisconsin, Madison 53706, Present address of senior author: Department of Plant Pathology, University of Arkansas, Fayetteville 72701; R. D. Durbin(2), and J. E. Kuntz(3). (2)Research Leader, Agricultural Research Service, U. S. Department of Agriculture, and Professor of Plant Pathology, Department of Plant Pathology, University of Wisconsin, Madison 53706; (3)Professor of Plant Pathology and Forestry, Department of Plant Pathology, University of Wisconsin, Madison 53706. Phytopathology 66:1295-1297. Accepted for publication 12 May 1976. Copyright © 1976 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-66-1295.

The diffusive resistance of individual leaves of northern red oak seedlings was measured with a diffusion porometer during the development of oak wilt. Stomatal resistance increased sharply approximately 3 days before visible symptoms became evident. Diffusion porometry provided a quick and nondestructive method for predicting this increase in diffusive resistance and subsequent symptom development.