Black Stem: A Fungal Disease of Common Purslane in California. J. M. Klisiewicz, Research Plant Pathologist, USDA, ARS, Department of Plant Pathology, University of California, Davis 95616. Stephen L. Clement, Research Entomologist, Biological Control of Weeds Laboratory, USDA, ARS, Albany, CA 94706; and Robert F. Norris, Associate Professor of Botany, University of California, Davis 95616. Plant Dis. 67:1162. Accepted for publication 24 June 1983. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1983. DOI: 10.1094/PD-67-1162.

A disease of purslane, a common weed in California, causes stem blackening and constriction at the soil line. Black lesions occasionally develop on upper stem parts. Infected roots become dark and constricted. Spread of the pathogen Dichotomophthora portulacae in the stems and root may result in death of purslane plants.