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Similarity of Annual Anthracnose Epidemics in Young Juglans nigra Plantations from 1978 Through 1982. Kenneth J. Kessler, Jr., Principal Plant Pathologist, USDA Forest Service, North Central Forest Experiment Station, Carbondale, IL 62901. Plant Dis. 68:571-573. Accepted for publication 11 January 1984. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1984. DOI: 10.1094/PD-68-571.

During 5 yr of observations (1978 through 1982) of walnut anthracnose development in young black walnut plantations, initial lesions arising from infections by ascospores always appeared in May. Lesion numbers increased through early summer as a result of secondary leaf infection by conidia. Disease development was maximal in late July and early August, when most defoliation of previously infected leaflets occurred. Leaf wetness periods of 12 hr or more, suitable for leaf infection, occurred with enough consistency each summer to perpetuate yearly anthracnose epidemics in similar fashions.

Keyword(s): Gnomonia leptostyla.