Genotypic diversity of Sphaeropsis sapinea from South Africa and Northern Sumatra

Sphaeropsis sapinea is the most important pathogen of Pinus spp. in South A frica. The fungus, which reproduces only asexually, occurs on exotic Pinus spp. In this study, the diversity of the S. sapinea population in South Afr ica was compared with a population from Northern Sumatra. The populations f or both countries were obtained from exotic Pinus patula plantations. The p henotypic diversity of these populations was assessed using vegetative comp atibility tests. The percent maximum genotypic diversity, based on Stoddart and Taylor's index, for the South African population was 30.5% compared wi th 1.5% for the Northern Sumatran population. Based on the number of phenot ypes, the South African S. sapinea population was significantly more divers e (P = 0.05) than that of the Northern Sumatran population. The results ind icate that the population of S. sapinea in South Africa has, in all likelih ood, arisen as a result of introductions of the fungus on pine seeds import ed from various parts of the world during the last century.