Disclosed is a method of reducing insect and microbial decay in wood. The method comprises the steps of:a) immersing the wood in a treatment solution comprising i) a C1-C6monoalkanolamine ester of boric acid (e.g., monoethanolamine ester of boric acid) and ii) creosote andb) exposing the immersed wood from step a) to conditions which cause the release of boron from the C1-C6 monoalkanolamine ester of boric acid (monoethanolamine ester of boric acid) and which cause the boron to migrate into the interior of the wood.
