Characterization of Fusarium Isolates from Gladiolus Corms Pathogenic to Pines. A. Viljoen, Department of Microbiology and Biochemistry, University of the Orange Free State, P.O. Box 339, Bloemfontein, 9300, South Africa. M. J. Wingfield, Department of Microbiology and Biochemistry, University of the Orange Free State, P.O. Box 339, Bloemfontein, 9300, South Africa; W. F. O. Marasas, Programme on Mycotoxins and Experimental Carcinogenesis, Medical Research Council, P.O. Box 19070, Tygerberg, 7505, South Africa; and T. A. Coutinho, Department of Microbiology and Biochemistry, University of the Orange Free State, P.O. Box 339, Bloemfontein, 9300, South Africa. PLANT DIS. 79:1240. Accepted for publication 6 March 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-1240.

Fusarium subglutinans is a well-known pathogen of many crops. The fungus causes a serious disease of pines known as pitch canker. A proposal has been made to designate isolates from pines F. subglutinans f. sp. pini (F. s. f. sp. pint). An enigma regarding the nomenclature is that some F. s. f. sp. pini isolates have been reported to induce decay of gladiolus corms whereas certain isolates of F. subglutinans from gladiolus corms were also found to be weakly to moderately pathogenic to pine seedlings. In this study we re-examined three previously studied isolates from gladiolus in the United States that had been referred to as F. subglutinans ( = F. moniliforme var. subglutinans) or F. moniliforme in the literature. We found that these isolates were typical of F. proliferatum. They were mildly pathogenic on pine seedlings and significantly less virulent than an isolate of F. s. f. sp. pini. Inoculation of gladiolus corms with these isolates of F. proliferatum from gladiolus, F. oxysporum from pine seedlings, and F. subglutinans from pines (F s. f sp. pini), corn, mango, and pineapple indicated that only isolates of F. proliferation were moderately pathogenic to gladiolus corms. This study therefore supports the proposal that isolates of F. subglutinans from pines represent a specific forma specialis within the species.