Sexual behaviour of Armillaria heimii and A. mellea isolates from Africa

Summary Thirty isolates ofArmillaria heimiifrom western, eastern and southern Africa were cultured for fruit body production in the laboratory. Most isolates fruited easily. Investigation of single‐spore progenies revealed that all the isolates do not have the same sexual behaviour: some are heterothallic and unifactorial while others are homothallic. Two African isolates belonging to the speciesArmillaria melleaalso appeared homothallic. Unifactorial heterothallism has not previously been described inArmillaria, species. Homothallic behaviour has been reported only in a rare European speciesArmillaria ectypaand in the Japanese subspeciesArmillaria melleassp.nipponica.