Wood is treated to reduce or prevent biodeterioration using boron compounds. A significant portion of the active boron is retained within the wood when leached. Boric acid is complexed with water-soluble bifunctional polyhydroxyl aromatic compounds, and the boric acid bifunctional polyhydroxyl aromatic complex is deposited into wood treated with a silicate. The complexing agents comprise polyfunctional compounds, including at least two hydroxyl groups, and one or more separate acid groups.
