Fusarium subglutinans f. sp. pini represents a distinct mating population in the Gibberella fujikuroi species complex

Fusarium strains in the Gibberella fujikuroi species complex cause diseases on a variety of economically important plants. One of these diseases, pitc h canker of Pinus spp., is caused by strains identified as Fusarium subglut inans f. sp. pini. Fertile crosses were detected Between F.subglutinans f. sp, pini strains from South Africa, California, and Florida. F, subglutinan s f,sp. pini strains were not cross-fertile with the standard tester strain s of six of the seven other mating populations of G. fujikuroi, Sporadic pe rithecia with ascospores were obtained in two crosses with the mating popul ation B tester strains. These perithecia were homothallic, and the ascospor es derived from these perithecia were vegetatively compatible with the mati ng population B tester strain parent, We concluded that fertile F, subgluti nans f. sp. pini isolates represent a new mating population (mating populat ion H) of G. fujikuroi and that they belong to a unique biological species in a distinct taxon.