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United States Department of Agriculture

Agricultural Research Service

Title: Soybean Diseases: Charcoal Rot

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

Submitted to: World Wide Web New Crops Center Purdue University Bulletin
Publication Type: Experiment Station
Publication Acceptance Date: November 20, 1998
Publication Date: N/A

Interpretive Summary: Soybean yield losses due to charcoal rot occur regularly. Yield losses of 20-30% caused by Macriohomina phaseolina fungus have been reported in some fields. 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. 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 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.

Last Modified: 11/22/2014
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