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Physiology and Biochemistry

Leaf Diffusive Resistance of Sunflowers Infected by Pratylenchus penetrans. David T. Kaplan, Graduate Research Assistant, Department of Plant Pathology, University of Massachusetts, Amherst 01002. Present address of senior author: Department of Plant Pathology, University of California, Riverside 92502; R. A. Rohde(2), and Terry A. Tattar(3). (2)(3)Professor, and Assistant Professor, respectively, Department of Plant Pathology, University of Massachusetts, Amherst 01002. Phytopathology 66:967-969. Accepted for publication 11 February 1976. Copyright © 1976 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-66-967.

Diffusive resistance measurements of leaves of sunflower with roots infected by small populations of lesion nematodes indicate that internal water status of otherwise symptomless plants may be lower than that of healthy plants. Younger plants showed greater diffusive resistance than did older plants; however, regardless of age, infected plants showed increased diffusive resistance in advance of healthy plants growing under similar conditions. Such moisture stress may induce the stunting commonly associated with lesion nematode infection.