Diseases of Alfalfa in Alabama. F. A. Gray, Plant Pathologist-Nematologist, Alabama Cooperative Extension Service, Auburn University, Auburn, AL 36830. R. L. Haaland and E. M. Clark, Associate Professors, Department of Agronomy and Soils and Departments of Botany, Plant Pathology and Microbiology, respectively; and D. M. Ball, Agronomist, Alabama Cooperative Extension Service, Auburn University, Auburn, AL 36830. Plant Dis. 64:1015-1017. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-1015.

A 3-yr survey of fields in Alabama showed several diseases associated with declining stands of mature alfalfa (Medicago sativa). These include anthracnose (Colletotrichum trifolii), Sclerotinia crown and stem rot (Sclerotinia trifoliorum), Rhizoctonia crown rot (Rhizoctonia solani), summer black stem and leaf spot (Cercospora medicaginis), charcoal rot (Macrophomina phaseolina), and the alfalfa stem nematode (Ditylenchus dipsaci). Rust (Uromyces striatus) severely damaged a seedling stand of alfalfa. Rhizoctonia crown rot, charcoal rot, and the alfalfa stem nematode are reported from the state for the first time. Eleven of 15 isolates of R. solani from diseased alfalfa crowns were pathogenic on seedling alfalfa. Six additional fungi and eight nematodes also were associated with the alfalfa plant.