Stilbenes, phenolic compounds rich in Scots pine (Pinus sylvestris L.) heartwood, have strong fungicidal properties. We studied the effect of stilbene extract as an impregnant for Scots pine sapwood in two in vitro fungal tests. In the first test, we studied the entrance and early colonization of fungi into the impregnated wood blocks. In the later test, the inhibition of wood degradation was studied in an ordinary mass loss test. Impregnation solution was crude ethanol extract obtained from extracting stilbene rich Scots pine heartwood chips from which the resin acids had been removed with hexane. Two different concentrations of the stilbene solution containing both pinosylvin and its monomethyl ether were impregnated into Scots pine sapwood with pressure. Impregnated wood samples were exposed to three brown rot fungi, Gleophyllum trabeum, Coniophora puteana and Poria placenta, growing on malt agar in petri dishes. The growth speed of the hyphae towards the wood blocks was measured. High concentration of stilbenes showed strong inhibitory effect against the growth of G. trabeum. Two weeks after the moment when the fungal hyphae had reached the edge of the wood block the relative amount of hyphae-originating chitin inside the wood blocks was measured by chitin test described in Plassard et al. (1982). For all the fungi, the wood blocks impregnated with the stilbene extract contained less chitin than the untreated controls. More detailed analysis on the chemical changes occurring in the wood samples during the decay process will be carried out.
Keywords: Impregnation, stilbenes, brown rot fungi, Pinus sylvestris, chitin
Authors
Lu J.
Punkaharju Unit, Finnish Forest Research Institute, Punkaharju, Finland
Harju A.M.
Punkaharju Unit, Finnish Forest Research Institute, Punkaharju, Finland
Venäläinen M.
Punkaharju Unit, Finnish Forest Research Institute, Punkaharju, Finland
Login to download the PDF