With the fruiting bodies of Armillariella mellea, a proliferation of the gills has been observed for several years, always in the same locality, in the valley of Bílý potok at Veveří Bitýška, county Brno, ČSSR. This proliferation occurred usually in the centre of the cap, but also elsewhere on its surface. Diseased fruiting bodies were used for cultivation of mycelium, which was then inoculated into tree stumps. In subsequent years, gill proliferation was observed in Pholiota mutabilis and Laccaria amethystina growing on those stumps, while untreated fruiting bodies remained normal. The authors consider this abnormality to be virus-induced, also comparing it with similar forms in Cantharellus cibarius and Clitocybe nebularis var. alba. They also mention a case of pore proliferation in Trametes gibbosa and proliferation in Clitocybe nebularis var. alba in another locality.
Blattný C., Kasala B., Pilát A., Santilliová-Svobodová J., Semerdžieva M. (1971): Proliferation of Armillariella mellea (Vahl in Fl. Dan. ex Fr.) P. Karst., probably caused by a virus. – Česká Mykologie 25(2): 66–74.
