In the first in vitro experiment, no pathogen growth was observed in any of the SC1 inoculated treatments. After 28 days, average pathogen growth (mycelia and/or rhizomorphs) of 13.8 ± 2.7, 18 ± 2.9 and 16.1 ± 3.4mm(mean of 18 Petri dishes ± SE) was measured in Armillaria infected and SC1 untreated larch, pine and fir barks, respectively (Fig. 2). No significant differences were observed between these three treatments (p > 0.05). No fungal growth was detected in untreated control barks.