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© 1992, The Board of Regents of the University of Nebraska on behalf of the University of Nebraska–Lincoln Extension. All rights reserved.


The cause, symptom, disease cycle, influencing factors, effects and control of black dot are described. Black dot of potato, a disease caused by the fungus Colletotrichum coccodes, was recognized in Australia and Europe, then was observed and described in Canada in 1921. Since then this disease has spread to many potato production areas of the United States; its occurrence was first reported in Nebraska in 1988. In the past few years, black dot has been recognized on infected potato tissue from several areas of the state. The increased incidence of black dot in Nebraska may have been favored by high temperatures and heavy irrigation. Black dot often has been reported as a minor disease. Under favorable conditions, especially on poorly drained, sandy soils, it can result in significant yield losses in the field and loss of quality of infected tubers in storage.