Microbial Attack of CCA-Treated Pinus radiata Timber from a Retaining Wall

Light and electron microscopic observations were made of Pinus radiata wood treated to a high retention of copper-chrome-arsenate (CCA), which had failed after approximately 11 years in service. The predominant wood cell wall degradation patterns seen under the light microscope and scanning electron microscope as channels and shallow depressions and which were probably responsible for failure of the pole were shown by transmission electron microscopy to be caused by erosion bacteria. Although this type of wood decay is known, the predominance of attack of deeper regions of the pole by erosion bacteria was unusual and significant in terms of the ecology of wood degrading bacteria. Soft-rot was seen in outer regions of the wood at the groundline but was very rarely seen in deeper regions