A wood preservative composition comprising 4,5-dichloro-2-octylisothiazol-3(2H)-one, a method of treating a wood substrate therewith, and a wood product produced therefrom are provided. The wood preservative composition comprises at least 0.5% by weight of DCOI based on the total weight of the composition and a retaining additive comprising a solvent-borne polymeric resin, a wax, or a combination thereof. A weight ratio of the DCOI to the retaining additive in the composition is in a range of 1:5 to 5:1.