VIEW ARTICLE

Cytology and Histology

Histopathology of Cotton Boll Rot Caused by Colletotrichum capsici. Rodney Golden Roberts, Former research associate, Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Experiment Station, Baton Rouge 70803, Present address of senior author: Department of Plant Pathology, University of Georgia, Athens 30602; J. P. Snow, professor, Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Experiment Station, Baton Rouge 70803. Phytopathology 74:390-397. Accepted for publication 12 September 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-390.

The histopathological aspects of cotton boll rot caused by Colletotrichum capsici were studied by using scanning electron and light microscopy. Class I (10- to 12-day-old) greenhouse-grown cotton bolls of two cultivars were resistant to invasion by C. capsici and exhibited a hypersensitive response characterized by restricted lesions, plasmolysis and collapse of host epidermal cells, and pigment accumulation in subepidermal parenchyma. Histochemical tests failed to detect gossypol or hemigossypol associated with the hypersensitive lesions. Class II bolls (34- 36 days old) were susceptible to invasion. Nonlignified pericarp cell walls became swollen and did not stain. Lignified pericarp tissues were more resistant to degradation and retained their staining properties. The distinctive appearance of bolls rotted by C. capsici is probably due to the differential degradation of pericarp tissues.