DURABILITY OF ANGIOSPERM HEARTWOOD - THE IMPORTANCE OF EXTRACTIVES

Analysis of osage orange (Maclura pomifera) heartwood extractives show ed that two compounds were present at much higher levels than previous ly reported, the flavanonol dihydromorin (2.51%) and the stilbene oxyr esverauol (2.65%). All compounds present in osage orange heartwood tha t were tested bad low activity against wood-decaying fungi. The agar p late test showed no synergistic effect, but the soil block test using white-rot fungi suggested synergism. The high durability of osage oran ge heartwood may be due to the large amounts of oxyresveratrol and dih ydromorin. High levels of one or two monomeric compounds may also expl ain the exceptionally good durability of black locust and red mulberry heartwood.