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Response of Ancestral Soybean Lines and Commercial Cultivars to Rhizoctonia Root and Hypocotyl Rot

October 2001 , Volume 85 , Number  10
Pages  1,091 - 1,095

C. A. Bradley , Department of Crop Sciences , G. L. Hartman and R. L. Nelson , USDA Agricultural Research Service and Department of Crop Sciences , D. S. Mueller and W. L. Pederson , Department of Crop Sciences, University of Illinois, National Soybean Research Laboratory, 1101 W. Peabody Dr., Urbana 61801

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Accepted for publication 15 June 2001.

Rhizoctonia root and hypocotyl rot is a common disease of soybean caused by Rhizoctonia solani. There are no commercial cultivars marketed as resistant to Rhizoctonia root and hypocotyl rot, and only a few sources of partial resistance to this disease have been reported. Ninety ancestral soybean lines, maturity groups (MGs) 000 to X, and 700 commercial cultivars, MGs II to IV, were evaluated for resistance to R. solani under greenhouse conditions. Most of the ancestral lines and cultivars evaluated were susceptible; however, 21 of the ancestral lines and 20 of the commercial cultivars were partially resistant. Of the 21 ancestral lines, CNS, Mandarin (Ottawa), and Jackson are in the pedigree of cultivars previously reported as being partially resistant to R. solani. In an additional study, dry root weights of 21 soybean cultivars were evaluated after inoculation with R. solani. Variation in dry root weight occurred among cultivars, but there was not a significant (P = 0.05) correlation between dry root weight and disease severity.

© 2001 The American Phytopathological Society