VIEW ARTICLE

Use of Morphology and Mating Populations in the Identification of Formae Speciales in Fusarium solani. Takken Matuo, Professor, Faculty of Textile Science, Shinshu University, Ueda, Nagano-ken, Japan; William C. Snyder, Professor Emeritus, Department of Plant Pathology, University of California, Berkeley 94720. Phytopathology 63:562-565. Accepted for publication 13 November 1972. DOI: 10.1094/Phyto-63-562.

Nine formae speciales and two races of Fusarium solani have been reported in the United States and Japan. They are sorted into four groups (A, B, C, D) by the morphologic characters of macroconidia which were formed on sporodochia under continuous illumination. Group A, composed of f. sp. cucurbitae race 1 and some isolates of race 2, f. sp. batatas, f. sp. mori, f. sp. xanthoxyli, f. sp. robiniae and an isolate of f. sp. eumartii, is characterized by predominant 5- (or more) septate macroconidia. The B group, which includes f. sp. pisi, f. sp. cucurbitae race 2 and several isolates of f. sp. eumartii, have predominant 3-septate macroconidia less than 5 µ in width. The C group, f. sp.radicicola, is characterized by predominant 3-septate macroconidia which are 5.5 µ or more in width. The D group, f. sp. phaseoli, has predominant 4-septate macroconidia. There was no significant difference in the morphologic characters of microconidia and Hypomyces stage, if present, among these formae speciales and races. Six formae speciales and two races have been known to have a Hypomyces stage. In mating and sexual behavior as well as morphology, these formae speciales and races are very similar to Fusarium (Hypomyces) solani f. sp. cucurbitae race 1, but they are distinctly isolated from one another with regard to mating population. From this fact, it was proposed that the crossing tests will be usable as a method for identifying formae speciales and races, where matings may be made, in addition to the pathogenicity tests.