Antagonism against fomes annosus. Comparison between different test methods in vitro and in vivo

The antagonism of Trichoderma harzianum, Scytalidium album and an unidentified fungus (isolated from Monotropa hypopitys) against the root rot fungus Fomes annosus was studied in vitro and in vivo. Antibiosis was demonstrated on malt extract agar and on powdered wood. Competition between F. annosus and its antagonists was studied in stem discs and in living stems of Norway spruce. Effective antibiotics on agar and sawdust did not always bring about effective antagonism against F. annosus in stem discs or living trees. Factors such as growth rate of the antagonists in wood and their ability to invade the substrate during competition may influence the effectiveness of F. annosus suppression. The results from studies on antagonism in stem discs agreed with the results from tests in living trees. The frequency of penetrations through the wood cell walls was drastically lowered by the presence of the antagonists but was not closely correlated with the abundance of F. annosus.