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Fungitoxic Action of a Copper-Chromium-Arsenate Wood Preservative. C. K. Chou, Hickson Fellow, Astbury Dept. Biophysics, Leeds University, England, Present address: Research Scientist, Forest Research Institute, Rotorua, New Zealand; R. D. Preston(2), and M. P. Levi(3). (2)Professor, Astbury Dept. Biophysics, Leeds University, England; (3)Head of Research, Hickson and Welch (Holdings) Ltd, Castleford, England, Present address: Associate Professor, Wood and Paper Science and Plant Pathology, North Carolina State University, Raleigh 27607. Phytopathology 64:335-341. Accepted for publication 13 September 1973. DOI: 10.1094/Phyto-64-335.

The interactions between wood treated with copper-chromium-arsenate (CCA) and several wood-destroying fungi were studied to obtain a clearer understanding of the in vivo mode of action of the preservative. The fungi varied considerably in their tolerance to CCA. Subtoxic amounts of preservative had little effect on colonization of the treated wood. Toxic amounts drastically reduced colonization except with Poria monticola. Copper, chromium, and/or arsenic were solubilized by all the fungi at both subtoxic and toxic levels. All the fungi except P. monticola remained viable in veneers treated with toxic amounts of preservative. Microscopic examination of treated wood showed that many of the hyphae were dead. P. monticola absorbed copper, chromium, and arsenic from the secondary walls of tracheids into the hyphae. Absorption of solubilized fungitoxicants into hyphae is probably the primary mode of action of the CCA although there was evidence that inhibition of cellulose decomposing systems also may play a role. The contradictory behavior of P. monticola in colonization and viability tests may be due to differences in the rates of absorption of copper and arsenic by the fungus.