Identification of the causal agent of Armillaria root rot in South African forest plantations.
Armillaria isolates were made from plantations of Pinus spp. (P. elliottii and P. patula) and Litchi chinensis in South Africa, and from plantations of Acacia xanthophloea and an unknown species in Zimbabwe. Isolates were also made of A. heimii from Pinus elliottii in South Africa, Pelargonium asperum in Réunion, Tectona grandis in Zambia, and an unknown species in Zimbabwe and Cameroon. All the isolates were characterized from RFLP (restriction fragment length polymorphism) and nucleotide sequence data of the intergenic spacer region between the large subunit and the 5S gene of the ribosomal DNA operon. The isolates were shown to be distinct from A. mellea and A. heimii, and may represent either an undescribed species of Armillaria or (possibly) A. fuscipes.