Biological control of Fomes annosus in Norway spruce (Picea abies) with immunizing commensals
Ricard, Jaques L.
All Norway spruces tested which survived prolonged exposure to F. annosus without damage were found to harbor microorganisms in their stem wood, while only 40 % of spruces tested at random yielded microorganisms. Several of the microbial isolates displayed antagonistic activities toward F. annosus, particularly Trichoderma album and Coryne sarcoides. Artificial inoculations of immunizing commensals (IC) in fresh log seclions of Norway spruce were successful only with Trichoderma album, Coryne sp. and bacteria. Scytalidium sp. FY strain could not be introduced successfully under those conditions. In only one instance did limited FY growth take place within the log, but it resulted in the formation of pathological zonation lines in the wood. Similar markings developed on the surface of dart-type inoculants, introduced in the live sapwood of Norway spruce. The lethal action of C. sarcoides on F. annosus is due at least in part to the release of a water-soluble antibiotic by the former organism. No such substance appears to be released by Trichoderma album, although that latter fungus was able to immobilize or utilize in the malt broth one or more nutrients essential for the development of F. annosrrs. In addition, photomicrographs show that hyphae of T. album curl about the pathogen, while a lysis of the hgphal membrane in F. annosus and coagulation of its cytoplasm occur. T. album was effective against the pathogen at 18-22°C and at 5°C.
biological control; Fomes annosus; Picea abies; Norway spruce
Studia Forestalia Suecica
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