Disease Note.

Ash Yellows in Green Ash in North Dakota. J. A. Walla, Department of Plant Pathology, North Dakota State University, Fargo 58105. C. L. Ash, Department of Plant Pathology, University of Minnesota, St. Paul 55108 and M. A. Draper, Department of Plant Pathology, North Dakota State University, Fargo 58105. Plant Dis. 78:432. Accepted for publication 24 January 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0432E.

Ash yellows (AshY), which was recognized as a significant disease of Fraxinus spp. in the United Slates during the 1980s, was confirmed in green ash (Fraxinus pennsylvanica Marshall) in 1992 in two Minnesota cities bordering North Dakota. In June 1993, AshY symptoms were found on three planted green ash trees in Cass and Ransom counties in southeastern North Dakota. Witches’-brooms consisting of a few shoots with shortened internodes, multiple branches from nodes, and some simple leaves were present near the base of the trunk of two of the trees. Witches’-brooms consisting of multiple current-year shoots and mostly simple leaves were growing from the root collar of the third tree. AshY was confirmed by the 4’,6-diamidino-2-phenylindole (DAPI) fluorescence test in roots from below each witches’-broom and with AshY-specil’ic monoclonal antibody (1) in a leaf petiole from one of those witches’-brooms. One of the infected trees had severe top dieback, whereas the other trees appeared vigorous with no dieback. This is the first report of AshY in North Dakota and in the Great Plains region of the United Slates.