First Report of Fusarium Root Rot of Alliaria petiolata . W. Chen, Illinois Natural History Survey; and Department of Crop Sciences, University of Illinois at Urbana-Champaign, 607 East Peabody Drive, Cham- paign 61820 . J. E. Schwegman, Division of Natural Heritage, Illinois Department of Natural Resources, 524 South Second Street, Springfield 62701. Plant Dis. 80:711. Accepted for publication 10 April 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0711A.
Alliaria petiolata (M. Bieb.) Cavara & Grande (common name: garlic mustard), a native of northern Europe, is an obligatory biennial herbaceous weed that invades woodland communities in the midwestern U.S. and adjacent parts of Canada (1,2). This invasive weed is now widespread in shaded plant communities throughout the northern two-thirds of Illinois, threatening the floristic structure of the herbaceous layer of woodlands (2). No effective control measures are available for established populations of Alliaria petiolata. A state-wide survey of Illinois was conducted in 1994 with an aim of identifying diseases that may have potential for biological control of Alliaria petiolata. A diseased second-year plant of Alliaria petiolata was collected from the Manito Prairie Natural Preserve, Tazewell County, on 18 May 1994. Disease symptoms of the plant included stunting, willing, root rot, and discoloration (reddish) of the crown. Fusarium solani (Mart.) Sacc, was isolated from the discolored crown. In four greenhouse pathogenicity tests (five to six replications each with five plants) conducted in 1994 and 1995 using a root dipping inoculation technique, isolate GM-7 of F. solani consistently caused significant disease of first-year plants of Alliaria petiolata. Symptoms observed on plants in these tests 4 weeks after inoculation included yellowing, wilting, root rot, crown rot, and death. Eighty to 90 percent of inoculated plants died, compared with no disease symptoms for noninoculated plants. The pathogen was reisolated consistently from the diseased test plants. This disease has potential for the biological control of Alliaria petiolata. The pathogenicity of this fungus on other native and crop plants remains to be tested. However, in greenhouse tests F. solani was not pathogenic to a Viola species that is a frequent cohabitant with Alliaria petiolata. This note represents the first report of Fusarium root rot of AlliariaReferences: (1) P. B. Cavers et al. Can. J. Plant Sci. 59:217, 1979 (2) V. A. Nuzzo. Nat. Areas J. 11:158, 1991.