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Cytology and Histology

Histopathology of Sweet Potato Roots Infected with Monilochaetes infuscans. G. W. Lawrence, Former graduate student, Department of Plant Pathology, North Carolina State University, Raleigh 27650, Present address of senior author: Department of Plant Pathology, Louisiana State University, Baton Rouge 70803; J. W. Moyer(2), and C. G. Van Dyke(3). (2)Assistant professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650; (3)Associate professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650. Phytopathology 71:312-315. Accepted for publication 23 July 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-312.

Infection of sweet potato roots by Monilochaetes infuscans occurred by direct penetration of cell walls. Conidia germinated within 6 hr, producing one or two germ tubes. Each germ tube terminated in an appressorium from which an infection peg penetrated the cell wall on the root surface. The fungus colonized the root periderm by growing intracellularly and forming appressorialike structures and infection pegs to facilitate cell-to-cell growth. Colonization was essentially limited to the periderm with occasional hyphae in the first layer of cortex cells. No appressoria were observed in the cortex. Infection and colonization of underground stem tissue was similar to that in the root periderm.