Developing environmentally benign and effective organic wood preservatives by understanding the biocidal and non-biocidal properties of extractives in naturally durable heartwood

Abstract Wood products for exterior residential applications have long been protected with metallic preservatives. However, environmental and disposal concerns and governmental regulations have resulted in a growing trend to employ organic systems based on relatively benign and expensive agrochemicals. To develop organic preservatives that have increased efficacy and lower cost, various groups are studying the biocidal and non-biocidal properties of extractives present in naturally durable heartwoods. In this study, we determined the fungicidal, free radical scavenger/antioxidant, metal chelation and Fe³⁺ reducing properties of some flavones and flavonoid analogs and chromones. The results support our earlier hypothesis that the abiotic antioxidant, Fe³⁺ reduction and subsequent metal complexation properties, in combination with the extractives’ fungicidal properties, all have a role in natural durability. Consequently, it may be possible to employ non-biocidal additive(s) with the above abiotic properties to enhance the efficacy of the relatively expensive organic agrochemicals used to protect wood.