Synergistic Wood Preservatives: Terrestrial Microcosms (TMCs) and Field Exposure Efficacy Studies of the Synergistic Copper: Pyrithione Mixture

Tor P. Schultz, Thomas Nilsson, Darrel D. Nicholas


On the basis of short-term laboratory tests using various wood decay fungi, we previously found that the mixture of copper (II) and sodium pyrithione is highly synergistic. In this study we examined the efficacy of this mixture in protecting wood using terrestrial microcosms (TMCs) with three different Swedish soils, and field stake (ground contact) tests in two different locations in Mississippi. After 12 months of exposure in TMCs, the copper: pyrithione mixture was found to be more effective than either component alone, with only slight degradation due to tunneling bacteria in a compost soil TMC. The field stake test, after 6 years of exposure, showed that a mixture of 0.31 pcf or greater copper (as CuO) and 0.063 pcf or greater pyrithione (as the sodium salt) was approximately as effective as about 0.35 pcf CCA in preventing fungal and termite degradation.


Copper;field exposure;fungi;pyrithione;termites;terrestrial microcosms (TMCs);tunneling bacteria;wood preservation

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