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Differences Among Bean Cultivars in Receptivity to Uromyces phaseoli var. typica. J. V. Groth, Associate professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108; N. V. Rama Raje Urs, plant pathologist, Dahlgren and Co., 1220 Sunflower Street, Crookston, MN 56716. Phytopathology 72:374-378. Accepted for publication 7 July 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-374.

Receptivity (number of uredia obtained per propagule applied) to rust (caused by Uromyces phaseoli var. typica) was measured on unifoliolate and trifoliolate leaves of six cultivars of bean (Phaseolus vulgaris). Differences in receptivity among cultivars were observed after precision inoculation of leaves having a range of ages and less precise inoculation of leaves of uniform age. Both methods showed cultivar differences in receptivity. Plants of cultivar Royal Red Kidney, which was least receptive overall, exhibited lower receptivity for both unifoliolate and trifoliolate leaves at every age than did those of the highly receptive cultivar Pinto 111. Differences in receptivity for these two cultivars over all ages were approximately threefold for both leaf types. Method of measuring receptivity influenced the results obtained; those made on leaves of different ages provided sufficient information for fully describing receptivity.