INFLUENCE OF THE ENHANCED NITROGEN IN AMMONIACAL COPPER TREATED WOOD ON DECAY BY BROWN AND WHITE-ROT FUNGI

Wood treated with ammoniacal copper based preservatives retains an enh anced nitrogen content. The effect of the enhanced nitrogen on the dec ay caused by two brown rot fungi and one white rot fungus was investig ated. A 5% ammonium hydroxide treatment reduced decay in conditioned b ut unleached blocks by P. placenta a to almost zero. However, leaching of the blocks resulted in an increasing weight loss with increasing a mmonia treatment by the same fungus. Although slightly reduced, T. ver sicolor produced a 22% weight loss in wood treated with 10% ammonium h ydroxide solution. G. trabeum was unaffected by the high ammonia level s, the weight loss actually increasing with increasing nitrogen. Treat ment with ammoniacal copper solutions to copper retention of 0.7kg/m(3 ) reduced weight losses to almost zero for G. trabeum and T. versicolo r but failed to prevent decay by the copper tolerant P. placenta. With increased ammonia content the mass losses caused by the brown rot fun gi increased.