Surveys on the distribution of Armillaria show that Armillaria heimii occurs in Kenya, Zimbabwe and the Congo. Armillaria mellea subspp. africana has only been found in Kenya. The local distributions of the different species in the various countries are discontinuous, confined to wetter regions at high elevations in Kenya, high to low altitudes in Zimbabwe and at low elevation in the Congo. They have a wide host range among indigenous and exotic trees and cash crops. In Kenya fruitbodies of both species, in particular Armillaria heimii occur in the field during the rainy season but are far more difficult to find than in Europe. Rhizomorphs are found in the soil in Kenya, especially at high altitude, but are more rare in Zimbabwe. Both species are pathogenic on young seedlings but Armillaria mellea may bo more pathogenic than Armillaria heimii. Some isolates however from highland Kenya do not belong to either Armillaria heimii or Armillaria mellea and constitute two other groups or species. In preliminary pathogenicity trials an isolate from one of these groups does not seem as pathogenic as Armillaria mellea or Armillaria heimii.
