Identification of the causal agent of Armillaria root rot of Pinus species in South Africa

Armillaria root rot was reported on economically important Pinus and Eucalyptus species grown in plantations in South Africa since the early 1900s. Armillaria species have been well studied in North America and Europe, but have received minimal attention in South Africa. Most reports of Armillaria root rot in South Africa suggest that A. mellea is the causal agent. The name A. heimii has also been used in more recent reports, although these have not been based on mycological studies. The taxonomic disposition of Armillaria in South Africa, therefore, remains unknown. The aim of this study was to identify and characterize Armillaria isolates from forest plantations in South Africa based on morphology, PCR-RFLP profiles and sequence data. Analysis of these characters revealed that the isolates originating from the plantations in South Africa are distinct from A. mellea and A. heimii. We believe that they represent A. fuscipes.