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Cytology and Histology

Histopathology of the Apical Leaves of a Susceptible Chrysanthemum Cultivar Infected with Fusarium oxysporum f. sp. chrysanthemi. Barbara A. Stuehling, Former graduate research assistant, Department of Plant Pathology, Fusarium Research Center, The Pennsylvania State University, University Park 16802; Paul E. Nelson, professor, Department of Plant Pathology, Fusarium Research Center, The Pennsylvania State University, University Park 16802. Phytopathology 71:1152-1155. Accepted for publication 20 February 1981. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-1152.

The apical leaves of Yellow Delaware chrysanthemum plants inoculated with Fusarium oxysporum f. sp. chrysanthemi were frequently chlorotic and asymmetric. The pathogen was not present in all leaves with these symptoms, nor was it absent from all symptomless leaves. Unequal tissue development on opposite sides of the midvein caused an asymmetric structure. Presence of the pathogen in the plant appeared to accelerate differentiation in leaf tissues. Vascular tissue throughout the entire lamina of infected plants was well differentiated, in contrast with the leaves of uninoculated plants.