Annular leaf spot of potato

Small round leaf spots are formed, with pronounced concentric ridges on the upper side. Lesions are rather similar to those caused by Alternaria solani, but they are not depressed. They are typically brown rather than black. With the help of a good magnifying glass, the relatively large black pycnidia may be observed on the upper side of lesions. In a more advanced stage, leaves become scorched and susceptible to wind damage. Leaf tissues finally become necrotic and leaves are dropped.

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Presence among species