​​​Black Dot Root Rot of Potato

December 2010 | 14 min., 49 sec.
by Barry Jacobsen
Montana State University


​Black dot is both a widespread and important disease of potatoes. The causal fungus, Colletotrichum coccodes, is found worldwide, has a broad host range, and can survive as sclerotia in soils for long periods. Yield losses of up to 40% have been shown for some cultivars in inoculated experiments, and many commonly grown cultivars have shown yield losses of 10–20%. Yield losses occur both through root rot and premature dying and from tuber blemishes that resemble silver scurf. Black dot is commonly involved in the early dying complex with Verticillium wilt and nematodes. Control of this disease can involve soil fumigation, use of seed treatments, in-furrow fungicide applications followed by postemergence fungicide applications, long rotations, and production practices that reduce stress. While no cultivars are immune, cultivars with <5% yield losses have been identified.

About the Presenter

Barry JacobsenBarry Jacobsen is a plant pathologist with research and Extension responsibilities. His areas of responsibility include research on potato and sugarbeet diseases, biological control of soilborne pathogens and noxious weeds, and development of integrated disease management programs. His Extension responsibilities include education programs on diseases of row crops, potato, and sugarbeet. His program involves the development of disease management strategies and IPM programs primarily for potatoes and sugar beets. Dr. Jacobsen received his bachelor’s and master’s of science degrees at the University of Wisconsin-Madison. He earned his PhD in plant pathology at the University of Minnesota.​

Contact Information:
Email: uplbj@montana.edu


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