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Disease Note.

Stem Canker of Black Walnut Caused by Fusarium solani in Kansas. N. Tisserat, Department of Plant Pathology, Kansas State University, Manhattan 66506. Plant Dis. 71:557. Accepted for publication 11 March 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0557D.

In April 1985, multiple trunk and branch cankers were noted on 64 of 184 trees in a 7-yr-old black walnut (Juglans nigra L.) plantation near Hutchinson, Kansas. The annual stem cankers often were more than I m long and occasionally extended to the soil line. Necrotic bark on the canker faces commonly sloughed off, exposing discolored sapwood. Fusarium solani (Mart.) Appel & Wollenw. emend. Synd. & Hans. (identified by T. A. Toussoun, Pennsylvania State University) was consistently isolated from the sapwood and cambium near the canker margins. Four-month-old black walnut trees were inoculated by inserting potato-dextrose agar containing mycelium and spores of F. solani into wounds. made in the bark. Inoculated trees developed sunken, black elongate cankers within I mo; F. solani was reisolated from the canker margins. Symptoms of the disease are similar to those on black walnut caused by F. sporotrichioides Sherb., F. lateritium Nees, and F. oxysporum Schl. (1,2). This is the first report of a canker disease of black walnut incited by F. solani.

References: (1) J. E. Cummings and J. E. Kuntz. Phytopathology 75: 1279, 1985. (2) K. J. Kessler, Jr. Plant Dis. Rep. 58:1044,1974.