VIEW ARTICLE

Uredial Development of Phakopsora pachyrhizi in Soybeans. M. A. Marchetti, Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, Plant Disease Research Laboratory, Frederick, Maryland 21701, Present address of senior author: ARS, USDA, Texas A&M University Agricultural Research and Extension Center, Beaumont 77706; F. A. Uecker(2), and K. R. Bromfield(3). (2)Botanist, ARS, USDA, Mycology Laboratory, Beltsville Agricultural Research Center-West, Beltsville, Maryland 20705; (3)Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, Plant Disease Research Laboratory, Frederick, Maryland 21701. Phytopathology 65:822-823. Accepted for publication 10 March 1975. DOI: 10.1094/Phyto-65-822.

Uredial primordia were evident in leaflets of ‘Lee 68’ soybeans 5-7 days after inoculation with uredospores of Phakopsora pachyrhizi. Sporulation from the first uredia started 9 days after inoculation, and continued for about 3 weeks. New uredia continued to form until about 4 weeks after inoculation. In contrast, uredia in P.I. 200492, a soybean accession with field resistance to rust, were about a day behind in development and senesced 2-4 days sooner than in Lee 68; new uredia continued to form in P.I. 200492 for about 3 weeks after inoculation.