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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Publications at this Location » Publication #198098
Title: DISEASES OF SOYBEAN: CHARCOAL ROT

Author
item WESTPHAL, ANDREAS - PURDUE UNIV.
item ABNEY, THOMAS
item SHANER, G - PURDUE UNIV.

Submitted to: World Wide Web New Crops Center Purdue University Bulletin
Publication Type: Experiment Station
Publication Acceptance Date: 6/11/2006
Publication Date: 6/11/2006
Citation: Westphal, A., Abney, T.S., Shaner, G.E. 2006. Diseases of soybean: charcoal rot. World Wide Web New Crops Center Purdue University Bulletin. 2p. Available at www.btny.purdue.edu/Pubs/index.html.

Interpretive Summary: Soybean yield losses due to charcoal rot occur regularly. Yield losses of 20-30% due to root and stem infections of soybean caused by the soil-inhabiting fungus Macrophomina phaseolina have been reported in some fields in years highly favorable for disease development. Disease development is particularly damaging in years with extended periods of hot, dry weather, although it occurs to some extent nearly every year, especially in southern Indiana. Although root infection can occur anytime during the season, symptoms of the disease may not be expressed until later in the growing season. The diagnostic symptom of charcoal rot is easily observed after plant death. Numerous, minute, black specks (‘pin-head size’ microsclerotia of the fungus that are hard masses of fungal tissue) can be seen when the epidermal tissue is peeled away from the lower stems and roots of affected plants. The microsclerotia survive in the soil and crop debris for 1-3 years or more, and are the primary source of inoculum for root infections. Cultural methods must be implemented to minimize charcoal rot damage. There are no fungicides or genetic resistance generally available in soybean varieties for effective disease control. 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. Information presented in this Soybean Disease Bulletin will permit extension specialists to diagnose disease development and recommend disease control strategies that can be used in soybean production to minimize yield losses.

Technical Abstract: Soybean yield losses due to charcoal rot occur regularly. Yield losses of 20-30% due to root and stem infections of soybean caused by the soil-inhabiting fungus Macrophomina phaseolina have been reported in some fields in years highly favorable for disease development. This bulletin summarizes the cardinal characteristics and disease cycle associated with charcoal rot of soybeans. Host range for the pathogen and disease control strategies are included in this bulletin. The information will be useful to extension and crop specialists in diagnosing and recommending control measures for soybean production where the disease is a major problem.