A method for treating a wood substrate is provided. The method comprises contacting the wood substrate in a field application with an aqueous composition. The contacting is performed at a pressure of less than 20 psia. The aqueous composition comprises, by total weight of the aqueous composition, 1.0% to 10.0% by weight of a micronized basic copper carbonate, 0.35% to 2.5% by weight of a quaternary ammonium compound, and at least 80% by weight of water.