Effects of Meloidogyne hapla and M. incognita on Phytophthora Root Rot of Alfalfa. Ronald E. Welty, Research Plant Pathologist, Southern Region, Science and Education Administration, Agricultural Research, U.S. Department of Agriculture, Raleigh, NC 27650. Kenneth R. Barker, Professor of Plant Pathology, N.C. State University, Raleigh 27650; and Donald L. Lindsey, Professor of Botany and Entomology, New Mexico State University, Las Cruces 88003. Plant Dis. 64:1097-1099. 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, 1980. DOI: 10.1094/PD-64-1097.

Sequential inoculation with either Meloidogyne hapla or M. incognita and Phytophthora megasperma f. sp. medicaginis intensified Phytophthora root rot severity in alfalfa cultivars resistant and susceptible to Phytophthora. M. hapla was more effective than M. incognita in exacerbating root rot symptoms, but both nematode species suppressed top and root growth, increased chlorosis, and reduced plant vigor. Inoculation with Phytophthora reduced the root mass available for nematode reproduction.

Keyword(s): nematode-fungus interactions.