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Extension is a Division of the Institute of Agriculture and Natural Resources at the University of Nebraska–Lincoln cooperating with the Counties and the United States Department of Agriculture
The environment plays a major role in the process of infection and disease development in plants by providing the conditions necessary for pathogens to cause disease. However, adverse environmental conditions or genetic abnormalities also may be responsible for plant damage. This type of damage often is referred to as abiotic disease or stresses. Many of the symptoms of these “diseases” may be confused with true dry bean diseases, thus this publication is designed to educate those working with dry bean on how to recognize abiotic problems and avoid unnecessary disease treatments.
The genetic abnormalities leading to changes in color in dry beans include chimeras, leaf spotting, yellowing. or production of albino plants or seedlings. Chimeras are among the most common genetic disorders. These aberrations, which may be inherited, result from a single site (point) cell mutation or from outcrossing during seed production. They may occur any time in the season. In leaf tissues, they cause a loss of chlorophyll, giving the leaf a white to yellow variegation (Figure 1). General chlorosis or yellowing traits (Figure 2) also may be inherited and are not likely to cause significant damage. However, the albino seedlings that may be observed early in the season, usually do not survive due to a deficiency of chlorophyll (Figure 3).