Performance of rubberwood (Hevea brasiliensis) against biodeterioration, when pressure-treated with Copper-Chrome-Arsenic (CCA) and Copper-Chrome-Boric (CCB) and exposed in Mandovi estuary (Goa) and in Kochi waters for a period of 32 months and 9 months respectively, has been discussed. The control panels were completely destroyed within a period of 4 to 6 months at both the localities. The resistance offered even by the treated panels was not encouraging, as infestation and damage to them were observed within 6 months of exposure. Though treatment at higher levels of retention was more effective, even these panels underwent 15 to 23% internal destruction at Goa and 12 to 16% destruction at Kochi within 9 months. Panels treated with both preservatives at lower and higher concentrations were rejected within 23 and 32 months respectively at Goa. Major borers present in the panels were Martesia striata, Nausitora hedleyi and Lyrodus pedicellatus. In general, there was no difference in the efficacy of CCA and CCB. Although failure of CCA and CCB-treated panels of some timber species has been reported earlier from these test stations, the present results emphasise the need for further trials so as to arrive at any reliable conclusion on improvement of durability by preservative treatment.

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