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United States Department of Agriculture

Agricultural Research Service

Title: Soybean Diseases: Sclerotinia Stem Rot (White Mold)

Authors
item Scott, Donald - PURDUE UNIVERSITY BOTANY
item Shaner, Greg - PURDUE UNIVERSITY BOTANY
item Abney, Thomas

Submitted to: World Wide Web New Crops Center Purdue University Bulletin
Publication Type: Experiment Station
Publication Acceptance Date: November 6, 1998
Publication Date: N/A

Interpretive Summary: Yield losses due to Sclerotinia stem rot (white mold) of soybeans in Indiana were rare prior to 1980 and slowly increased during the 1980s. However, during the 1990s, weather conditions have been especially favorable for disease. The increased incidence and severity of white mold is of concern because sclerotia (black, hard masses of fungal tissue) produced by the Sclerotinia sclerotiorum fungus can be easily spread to non-infested fields. The first symptom of Sclerotinia stem rot appears as a bleached area on infected stems during the pod and seed development growth stages. When stems are girdled by the disease, the soybean plant wilts and dies. The diagnostic sign is the presence of large (1/16 to 3/4 inch), hard, black, irregularly shaped sclerotia on stems in the white mold growth and within the stem pith tissue. Currently, there are no highly resistant varieties available, but some varieties are more tolerant than others. The fungal pathogen does not occur in some fields, and the spores that develop in the sclerotial tissue do not spread from field to field during the growing season. No single disease management practice will eliminate Sclerotinia stem rot; therefore, the integration of several practices is suggested. Management measures are aimed at reducing the spread of the pathogen to new areas, reducing the inoculum potential within affected fields, and minimizing disease losses in affected fields. The information describing symptoms, disease cycle, and control outlined in this publication will provide crop specialists and soybean growers current insight into disease diagnosis and management practices that will reduce disease losses.

Technical Abstract: Yield losses due to Sclerotinia stem rot (white mold) of soybeans in Indiana were rare prior to 1980 and slowly increased during the 1980s, but during the 1990s, weather conditions have been especially favorable for development of the fungal. The increased incidence and severity of white mold is of concern because sclerotia produced by the Sclerotinia sclerotiorum fungus can be easily spread to non-infested fields. This bulletin summarizes the cardinal characteristics and disease cycle associated with SDS of soybeans. Diagnostic characteristics associated with the fungal pathogen, soybean disease symptoms, host range and disease control strategies are included in this bulletin. The information describing symptoms, disease cycle, and control outlined in this Extension Publication will provide crop specialists and soybean growers current insight into disease diagnosis and management practices that will reduce disease losses.

Last Modified: 10/20/2014
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