The occurrence of Phellinus tremulae (Bond.) Bond. and Borisov as a primary parasite in Populus tremula L.

Phellinus tremulae was inoculated on Populus tremula . It spread in the sapwood and inner wood of a living tree without other organisms being present. Plating experiments with wood meal from different parts of a sound tree showed that there were very few, if any, propagules of micro organisms in the sound wood, neither were there any organisms found in front of the decay of P. tremulae at the top of the decay column. These results support the theory that P. tremulae is a primary parasite in aspen. Decay fungi grown on fresh and autoclaved wood of aspen had very different growth rates. Most of the fungi tested grew best on autoclaved sapvvood. The difference in growth rate on fresh and autoclaved heartwood was lcss significant, suggesting that there is a barrier in the living wood which is destroyed by autoclaving. P. tremulae was thc only fungus that grew best on fresh inner wood.