Tolerance of intersterility group isolates of Heterobasidion annosum to low pH and aluminium on solid medium

Tolerance of several strains of the P-, S-, and F- intersterility groups of Heterobasidion annosum to low pH and high concentration of aluminium ions was studied on malt extract agar. There were marked intraspecific, but not intergroup, variations in tolerance to both factors. Some strains were relatively tolerant or sensitive to low pH and aluminium, while the others were tolerant to low pH but sensitive to Al. There was no relationship between tolerance of the strains to low pH and their tolerance to aluminium stress.