A sometimes devastating root rot fungus, Armillaria, has been reported from many parts of the world and on a wide variety of hosts. Armillaria spp. are capable of killing healthy trees, attacking stressed trees and can be saprophytic decayers of dead trees. Armillaria root rot usually becomes apparent when indigenous forests are cleared for afforestation. The fungus colonises the remaining tree stumps and these serve as an inoculum base for the pathogen, that can then infect plantation species. In South Africa, this fungus is relatively uncommon. This is probably due to the fact that indigenous forests are uncommon and few plantations have been established on stands where large indigenous trees have been clear-felled.