AbstractThe effect on growth and rhizomorph formation of 12 alcohols (methanol, ethanol, 1‐propanol, 2‐propanol, 1‐butanol, 2‐butanol, iso‐butyl alcohol, tert‐butyl alcohol, 1‐pentanol, iso‐amyl alcohol, ethylene glycol and glycerol) at different concentrations has been examined for 2 isolates ofArmillaria mellea(Vahl ex Fr.) Quél. and 1 ofClitocybe geotropa(Bull. ex Fr.) Quél. The fungi were cultivated for 28 days on a synthetic, liquid glucose medium with the alcohols as supplement.The following alcohols strongly stimulated growth and rhizomorph formation: ethanol, 1‐propanol and 1‐butanol. A great variation was demonstrated between the isolates in relation to rhizomorph production, morphology, and ability to be stimulated