Copper tolerance by wood decay fungi is one of the most important problems in the field of wood preservation. These fungi are potential danger for preserved wood in use, wood with expected lifetime of 30 years. Although, the nature of the fungal tolerance is still not completely understood. The resistance of some species of wood decay fungi to copper has been connected to their production of copious amounts of oxalic acid. However, oxalic acid production is not the only factor responsible for this phenomenon. Laboratory experiments showed that one other important mechanism is active copper transport of copper tolerant fungi and diffusion of copper by intolerant ones
