Serpula lacrymans (Wulfen : Fries) Schröter, the dry rot fungus, is considered the most

(Wulfen : Fries) Schröterthe dry rot fungus, is considered the most

economically important wood decay fungus in temperate regions of the world i.e. northern

Europe, Japan and Australia. Previously copper based wood preservatives were the most

commonly used preservatives for pressure treatment of wood for building constructions.

Because of a suspicion about tolerance toward copper components, a soil block test was

undertaken to clarify the effect of two copper based preservatives, copper citrate and ACQ-D,

on the dry rot fungus, Serpula lacrymans compared to an alternative non-copper containing

wood preservative. The extensive use of copper-based wood preservatives has hastened the

need for understanding why some fungi are able to attack copper-treated wood. The copper

tolerance of S. lacrymans and other brown-rot fungi is thought to be due in part to oxalic acid

production and accumulation. Oxalic acid has been implicated in copper tolerance by the

formation of copper oxalate crystals. Twelve isolates of the dry rot fungus, S. lacrymans and

four other brown rot species were evaluated for weight loss on wood treated with 1.2% copper

citrate, 0.5% ACQ-D and 0.5% N'N-naphthaloylhydroxylamine (NHA). Eleven out of 12 S.

lacrymans were shown to be tolerant towards copper citrate. ACQ-D and NHA, on the other

were shown to be tolerant towards copper citrate. ACQ-D and NHA, on the other

hand, were both effective against the dry rot isolates. These wood preservatives are less toxic

toward the environment than traditional copper based preservatives.