The centers often degrade with time, resulting in circular holes in the foliage. Initial symptoms include dark flecks on the leaves that spread into lesions. armoraciae is more likely to cause infections in warmer temperatures. This disease is most prevalent during periods of cool, wet weather. Unfortunately, this form of bacterial leaf spot is readily spread by splashing water, including irrigation water, and by insects. In the case of a severe infection, the foliage can die. These spots can join together to form angular lesions, which make the leaves look ragged. It causes spots to form on the leaves that start out small, becoming dark brown or purple as they increase in size.
maculicola can infect all types of cole crops. maculicola and Xanthomonas campestris pv. There are two different species of bacteria that can cause bacterial leaf spot in cabbage, Pseudomonas syringae pv. These include the use of drip irrigation, sanitizing your gardening tools, rotating your crops, and removing all dead plant material at the end of the growing season.īiopesticides that may prove effective in the case of an outbreak include Bacillus amyloliquefaciens and Bacillus subtilis. As the disease develops, the spots join together to form large areas of dead tissue.Ĭontrols for Alternaria leaf spot start with good cultural practices.
As the tissue dies, the centers may fall out, resulting in holes in the foliage. Symptoms include yellow spots that grow larger and develop rings around them like a target or bull’s-eye. Photo by Elizabeth Bush, Virginia Polytechnic Institute and State University, .Īlternaria is more likely to cause disease when moisture is present on the cabbage, and temperatures range from 68 to 81☏. brassicae.īoth species are well known for causing leaf spots to develop on older tissue, but these fungi can also infect the base of the developing heads.
Alternaria leaf spot is caused by two species of fungi, Alternaria brassicicola and A.
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