Pathogenicity of the Columbia Root-Knot Nematode (Meloidogyne chitwoodi) to Onions. B. B. Westerdahl, Department of Nematology, University of California, Davis 95616. C. E. Anderson, E. M. Noffsinger, H. L. Carlson, P. A. Roberts, and A. Weiner. Department of Nematology, University of California, Davis 95616; University of California, Intermountain Research and Extension Center, Tulelake 96134; Department of Nematology, University of California, Riverside 92521; and Division of Plant Industry, California Department of Food and Agriculture, 1220 N Street, Sacramento 95814. Plant Dis. 77:847. Accepted for publication 5 April 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0847C.