Abstract

Sirmah Peter1,3 , Glassion Chelule2 , Hitimana Joseph 1 and Njue Naomi

Studies were carried out to understand the contribution of fungi to premature failure of Copper Chrome Arsenate (CCA) treated Eucalyptus grandis poles used in Kenya for structural purposes. Wood chips from ground line contact in CCA treated E. grandis poles were cultured and re-cultured in laboratory under sterile conditions, 25°C and relative humidity of 75% for 10days. The fungus obtained was further cultured in 100, 500 and 1000ppm CCA in Potato Dextrose Agar (PDA) and growth inhibition evaluated. Fungal growth inhibition ranged from 38% to 82% at 100 to 1000ppm CCA respectively. Wood specimens treated with1000ppm CCA or not treated and exposed to the fungus in a standard laboratory soil bed gave weight losses of 8% and 28% respectively. It is concluded that the fungus was able to detoxify copper as evidenced by the formation of brown ring during initial stages of decay and growth. It is not only through copper detoxification and tolerance that the fungus is able to bring about premature wood failure. Soil pH, site factors and CCA leaching as reported in similar studies, work in a synergistic manner to accelerate the failure of CCA treated wood poles, explaining the huge losses experienced in Kenya.