Even though metal nanoparticles are effective in protecting wood, they are less preferred, as they are synthesised using methods which are expensive and are not environmentally friendly. Biological synthesis of nanoparticles using plants, fungi, yeast, bacteria and viruses, has been accepted as an alternative approach and is referred to as green synthesis. Utilization of biologically synthesised nanoparticles is a new approach in wood protection. In the present study, copper oxide and zinc oxide nanoparticles were synthesised using leaf extracts of, Azadirachta indica A. Juss, Pongamia pinnata L Pierre, Lantana camara L, Chromolaena odorata L. R.M. King & H. Rob, Ocimum sanctum, Parthenium hysterophorus L and Nerium oleander L respectively. The formulation of leaf extracts and the synthesised nanoparticles were tested for their efficacy as a wood preservative as per BIS standards against termites, wood decay fungi (Trametes hirsuta Wulf. ex Fr., White-rot and Oligoporus placenta (Fr.) Gilb. and Ryvarden, brown-rot) and wood borer (Lyctus africanus Lesne). After one year of field evaluation, it was observed that control stakes were destroyed completely as an indication of active termite infestation. Formulation of P. hysterophorus leaf extract and CuO nanoparticles protected the treated rubberwood specimens from termite attack for a period of three months and CuO-P. pinnata for six months. Whereas formulations of L. camara, N. oleander and A. indica leaf extract with CuO nanoparticles protected the treated rubber wood specimens for a period of seven months. C. odorata leaf extract and CuO nanoparticle formulation gave complete protection to the treated rubberwood specimens for a period of 12 months. Results of the laboratory assay indicated that, when compared to control blocks, the formulation of L. camara leaf extract and CuO nanoparticles effectively protected the treated rubberwood from the attack of both white-rot and brown-rot, whereas the formulation of N. oleander leaf extract, CuO and ZnO nanoparticles protected brown-rot attack only. Formulation of leaf extracts of A. indica and L. camara with CuO nanoparticle were found to be effective against the Lyctus africanus Lesne for a period of two years. Leaching studies were conducted as per AWPA and the ability of chitosan to prevent leaching and its effect on efficacy was also evaluated. It was observed that dip treatment with chitosan (5%) significantly prevented the leaching of copper ions from the treated rubberwood specimens. Further studies are required to assess the stability, shelf life and toxicity of the formulation in order to recommend it as a commercially viable wood preservative.

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