The eucalypt plantation industry in South Africa is an important source of revenue for the country.
Eucalypt trees have been planted in the country for more than 200 years, as ornamentals, sources of
fuel and construction wood, and more recently also for the production of paper and rayon, amongst
other uses. The planting of eucalypts in South Africa has contributed to the development of many
forestry industries. It has also reduced the logging of indigenous forests. Eucalypts in South Africa
are, however, affected by numerous pests and pathogens. These include native South African pests
and pathogens, as well as those introduced from other countries. Of the pathogens, those commonly
reffered to as pathogenic Ophiostomatoid fungi, particularly species of Ceratocystis and
Ophiostoma are probably the best known. In recent years, some fungal species in the genera
Ceratocystis and Ophiostoma have emerged as important threats to plantation forestry globally and
it is critical to understand these fungi in order to reduce their future impact on eucalypts. In this
dissertation, Ophiostomatoid fungi that infested eucalypt trees in Australia and South Africa, that
were also identified from nitidulid beetles that visit these hosts, were identified using morphology
and DNA sequence data. As a foundation for the studies in the dissertation chapter one provided a
review of the literature pertaining to insects in the Nitidulidae and their association with fungi
including Ceratocystis spp. In chapters two and three, four new taxa, C. tyalla, C. corymbiicola, O.
tasmaniense, O. undulatum as well as four previously known species, C. pirilliformis, Ophiostoma
quercus, O. tsotsi, Pesotum australiae were identified from eucalypts in Australia. The four new
taxa were not pathogenic to E. grandis seedlings in greenhouse inoculation studies. In the last two
chapters, seven Ceratocystis and five Ophiostoma spp. were identified from various Eucalyptus
spp. and including some isolated from nitidulid beetles in South Africa. The Ceratocystis spp.
included two new taxa (C. salinaria, C. decipiens) and five known species, C. eucalypticola, C.
pirilliformis, C. moniliformis, C. oblonga, C. savannae. The Ophiostoma spp. included two new
taxa of the Ophiostoma stenoceras-Sporothrix schenkii species complex (O. candidum, O. fumeum)
and three known species (O. quercus, O. tsotsi, O. tasmaniense). The new taxa of Ceratocystis and
Ophiostoma identified in South Africa were not pathogenic to E. grandis seedlings in a greenhouse
inoculation studies. Most of the fungi identified were encountered on some nitidulid insects, and
four of these fungi where found in both Australia and South Africa. This suggests an
intercontinental movement of Ceratocystis and Ophiostoma, probably mediated by insects, in
particular nitidulid beetles.