BIOLOGICAL PROTECTION OF CONIFERS AGAINST HETEROBASIDION INFECTION - INTERACTION BETWEEN ROOT-ROT FUNGUS AND PHLEBIOPSIS GIGANTEA.

The biological control agent Rotstop, composed of spores of Phlebiopsis gigantea, is used for treatment of conifer stumps to reduce the spread of Heterobasidion root rot in commercial forests. Two experiments were conducted to compare the antagonistic ability of the Rotstop isolate and nine Latvian isolates of P. gigantea against root rot fungus Heterobasidion, in wood of Scots pine and Norway spruce. Billets of conifer trees were first sprayed with a spore suspension of P. gigantea and then with Heterobasidion at different concentrations. The presence of fungi in billets was evaluated by morphological characteristics of mycelium. The Latvian isolates of P. gigantea showed similar or even higher values of efficacy against Heterobasidion (average efficacy 84% in spruce and 89% in pine) than the commercially manufactured Finnish preparation Rotstop (61% in spruce and 90% in pine). Latvian isolates of P. gigantea have a potential to be used for preparation of biological control agents in the future. [ABSTRACT FROM AUTHOR]