VIEW ARTICLE

Cytology and Histology

Some Ultrastructural Observations of Cladosporium caryigenum Growth in Pecan Leaves. A. E. Rushing, Department of Biology, Baylor University, Waco, TX 76798; A. J. Latham, Department of Plant Pathology, Alabama Agricultural Experiment Station, Auburn University 36849. Phytopathology 81:1102-1108. Accepted for publication 10 June 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-1102.

After the fungus Cladosporium caryigenum infected pecan leaves, hyphae grew subcuticularly over both upper and lower leaf epidermal cells. Hyphae also extended into the leaf interior through the middle lamella of adjacent epidermal cells. All hyphal growth was intercellular. Conidiophores arose from bulbous cells that developed on branches of the subcuticular hyphae. Cell walls of the bulbous cells became melanized before conidiophore development. Extension of C. caryigenum conidiophores occurred by elongation of the bulbous cell and rupture of host cuticle. There was an accumulation of vesicles in the fungal cell near the point of rupture of the host cuticle. A collar, formed by the ruptured cuticle, surrounded the base of the conidiophore. Clusters of concentric bodies were found in conidiogenous cells, but not in vegetative hyphae.