VIEW ARTICLE

Penetration and Degradation of Cell Walls in Oaks Infected with Ceratocystis fagacearum. I. B. Sachs, Research Technologist, Forest Products Laboratory, Forest Service, USDA, Madison, Wisconsin, 53705; V. M. G. Nair(2), and J. E. Kuntz(3). (2)Assistant Professor, College of Environmental Sciences, University of Wisconsin, Green Bay 54301; and (3)Professor, Department of Plant Pathology, University of Wisconsin, Madison 53706. Phytopathology 60:1399-1404. Accepted for publication 14 April 1970. DOI: 10.1094/Phyto-60-1399.

Ceratocystis fagacearum initially invades the xylem vessels of the outer sapwood in infected oaks. Later, hyphae penetrate into the adjacent xylem parenchyma through the pits. Thereafter, hyphae grow intercellularly, intracellularly, and within the cell wall itself. Thus, the fungus also degrades the walls of infected sapwood cells, including the middle lamella. Lysis progresses from the lumen outward, much like the thinning action of white rot or stain fungi. Both the cellulose and lignin are affected. Hyphal penetration within the cell wall leads to cavities of varying size, shape, and direction. Electron-dense material forms within invaded and adjacent parenchyma cells. Fine structure of conidia and hyphae is described.