EN
Snyder et Hansen in 1940 simplified nomenclature and taxonomy of the genus Fusarium by minimizing the significance of morphological variation. On the basis of host-specificity they established formae speciales and included them in a single species Foxysporum Schlecht. emend. Snyder et Hansen. Up to date over 120 host-plants of nearly the same number of formae speciales have been recognized. Formae speciales were differentiated by means of pathogenicity tests and additional methods: serological, biochemical, genetic, vegetative compatibility tests and molecular biology analysis, as RFLP and PCR. Recently the differentiation of vegetative compatibility groups (VCGs) seems to be important in the characteristics of formae speciales. A systematic numbering of VCGs was proposed for standarization of the system used for categorizing genetic diversity in Foxysporum. It might be the beginning of a new taxonomic system of Fusarzum oxysporum.