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Anatomy of Leaf Abscission Induced by Oak Wilt. David TeBeest, Research Assistant, Department of Plant Pathology, University of Wisconsin, Madison 53706; R. D. Durbin(2), and J. E. Kuntz(3). (2)USDA Laboratory Leader for Pioneering Research Laboratory 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 63:252-256. Accepted for publication 23 August 1972. DOI: 10.1094/Phyto-63-252.

Oak wilt-induced leaf abscission was compared to artificially induced and natural leaf abscission in mature and juvenile red oak trees. In infected trees, the abscission process was indistinguishable from natural deciduous leaf abscission, both of which resulted from lysis of cell walls in the separation layer. Abscission of debladed petioles from healthy juvenile oaks developed from a cell division layer not found in natural or disease-induced abscission. Leaf abscission was not induced in drought-killed or deep-girdled trees. The results suggest that oak wilt-induced leaf abscission may be physiologically similar to natural abscission.