First Report of Fusarium oxysporum on Clary Sage in North America. V. P. Subbiah, Tobacco Company, Avoca Division, Merry Hill, NC 27957 . M. Riddick, and D. Peele, R. J. Reynolds, Tobacco Company, Avoca Division, Merry Hill, NC 27957; and M. A. Cubeta, Department of Plant Pathology, North Carolina State University, Plymouth 27962. Plant Dis. 80:1080. Accepted for publication 26 June 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-1080A.
Clary sage (Salvia sclarea L.) is grown commercially in California, North Carolina, and Oregon for its essential oil and flavor compound sclareol. Six fungal diseases have been previously reported on clary sage: anthracnose (Colletotrichum dematium (Pers.) Grove), Ascochyta blight (Ascochyla sclareae (Sarwar)), Phomopsis blight (Phomopsis sclareae (Sarwar)), leafspot (Podospora inaequalis), powdery mildew (Erysiphe polygoni DC), and Rhizoctonia root rot (Rhizoctonia solani KUhn) (1-4). None of these diseases has been reported from North America. In the summer of 1995, a seedling disease was observed in five clary sage production fields in North Carolina that reduced plant stand 40 to 50%. Diseased clary sage seedlings were stunted and roots exhibited reddish brown vascular discoloration and rotting. Diseased seedlings collected from each field were surface disinfested with 0.5% sodium hypochlorite for 3 min, rinsed with sterile distilled H2O, placed on sterile filter paper in a moist chamber for 5 days at 26°C, and examined microscopically. Fungi developing from infected seedlings were isolated by spreading single spores on water agar. Isolations from vascular tissue of infected seedlings consistently yielded (>90%) Fusarium oxysporum Schlech-tend:Fr. Species identification was confirmed by P. E. Nelson, Fusarium Research Center, The Pennsylvania State University, University Park. Four F, oxysporum strains from different fields were evaluated for pathogenicity. Forty 2-week-old clary sage seedlings (cvs. Early and English) were inoculated by dipping in a F. oxysporum suspension (1 x 106 conidia/ml) and planting in pasteurized potting mix. Seedlings dipped in sterile H2O served as controls. In another experiment, seeds and seedlings were sown in pasteurized potting mix amended with rye kernels precolo-nized with F. oxysporum (10% wt/wt). Seeds and seedlings sown in pasteurized potting mix amended with noncolonized rye kernels served as controls. There were three replicates of each treatment and experiments were conducted twice. Inoculated seedlings were incubated in the greenhouse at 21 to 25°C for 2 to 3 weeks. All seedlings either dipped in a spore suspension or grown in potting mix with precolonized rye kernels of each F. oxysporum strain were stunted with root rot and died within 3 weeks. Control seedlings were healthy and exhibited no symptoms or death. F. oxysporum was recovered from 90% of the infected seedlings to complete Koch's postulates. This is the first report of a disease on clary sage caused by F. oxysporum. This seedling disease may become a major limiting factor in the production of clary sage.References: (1) A. Pisi and M G. Bellardi. Inf. Fitopatol. 37:57, 1988. (2) M. Sarwar Indian J. Microbiol. 17:148, 1977. (3) A. D. Sharma and C. L. Jandaik Indian J. Mycol. Plant Pathol. 9:86, 1979. (4) S. I. Udagawa and T. Muroi. Trans. Mycol. Soc. Jpn. 20:13, 1979.