Nodulation: A Plant Disease Perspective. C. P. Vance, Agricultural Research, SEA, USDA, and University of Minnesota, St. Paul. L. E. B. Johnson, Agricultural Research, SEA, USDA, and University of Minnesota, St. Paul. Plant Dis. 65:118. . 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, 1981. DOI: 10.1094/PD-65-118.