American Phytopathological Society
April 2004
Interpretive summary

Mycelial Compatibility Grouping and Aggressiveness of Sclerotinia sclerotiorum.
L. S. Kull and W. L. Pedersen, Department of Crop Sciences, University of Illinois, Urbana 61801; D. Palmquist, United States Department of Agriculture–Agricultural Research Service (USDA-ARS), MWA Biometrician, Peoria, IL; and G. L. Hartman, USDA-ARS and Department of Crop Sciences, National Soybean Research Center, University of Illinois, Urbana. Plant Dis. D-2004-0120-02R, 2004 (online). Accepted for publication 25 October 2003.

On soybean, Sclerotinia stem rot is an important yield-reducing disease in the United States. Isolates of the fungus that cause this disease vary in several ways, including how fast they can colonize soybean tissue and what asexual group they belong to. In this study, isolates from two fields in Illinois and from other locations were compared. Among 299 isolates tested, 42 asexual groups were identified. Experiments testing isolate aggressiveness indicated a large variation among isolates. A soybean cultivar–isolate interaction was not detected, but resistant and susceptible cultivars performed similarly when inoculated with either less-aggressive or highly aggressive isolates. This study is important in documenting how different isolates from various geographic regions group together based on several attributes, and may be useful to other soybean pathologists, mycologists, and soybean breeders who have an interest in soybean fungal pathogens. Pathogen population structure and variability in isolate aggressiveness may be important considerations in disease-management systems.

Plant Disease is a leading international journal of applied plant pathology, published by The American Phytopathological Society. It publishes original research articles focusing on practical aspects of plant disease diagnosis and control. Each issue also includes a monthly feature article summarizing a significant topic in plant pathology. The Disease Notes section contains timely reports of new diseases, outbreaks, and other pertinent observations. For a full list of contents, visit http://www.apsnet.org/pd/current/.

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