The information and recommendations in this newsletter are applicable to North Carolina and may not apply in other areas.
The information and recommendations in this newsletter are applicable to North Carolina and may not apply in other areas.
From: Steve Koenning, Extension Plant Pathologist
Bacterial blight of cotton (also called angular leaf spot) has been detected in Chowan County, North Carolina. This is an important and potentially destructive bacterial disease of cotton. The disease is caused by a bacterium, Xanthomonas campestris pv. malvacearum. Cotton yield losses in excess of 10 percent have been reported in the past, although significant losses to this disease in the United States have not been reported in many years. At this time I do not know if this is an isolated incident, or may be a more wide spread problem. Thus far, only one variety Deltapine 425 is known to be affected. Some if not most cotton varieties may be resistant to this disease. The disease can be seed transmitted, but I cannot rule out the possibility that the disease causing bacterium survived the winter on crop debris to infest the current crop. Symptoms of this disease on cotton foliage are a distinctive leaf spot. The leaf spots tend to be angular with a red to brown-colored border. The angular appearance is due to restriction of the lesion by fine veins of the cotton leaf. Spots on infected leaves may spread along the major leaf veins. As disease progresses, leaf petioles and stems may become infected resulting in premature defoliation. Black cankers on stems may girdle the plant causing the upper portions to die. A white waxy crust containing the bacterium may form on old leaf spots or cankers. Bolls may become infected and this bacterium can contribute to boll rots. Infected bolls have round, rather than angular, lesions that may appear water-soaked initially. As infection of the bolls proceeds, the lesions will be sunken and dark brown or black in color. Growers, consultants, and scouts should identify infested fields, and determine the cotton variety as well as seed lot if possible.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on August 1, 2000 by Stephen J. Toth, Jr.