Disclosed is wood comprising a wood preservative composition, the composition comprising: (a) a dispersion in water of a biocidally effective amount of particles of a copper compound having a particle size of between 0.005 and 25 microns and (b) a biocidally effective amount of one or more organic biocides, wherein: the copper compound is selected from the group consisting of cupric oxide, cuprous oxide and copper oxychloride the one or more organic biocides is selected from the group consisting of cyproconazole, propiconazole, tebuconazole, 2-(thiocyanatomethylthio), benzothiazole, chlorothalonil, dichlofluanid, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (Kathon 930), a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (Kathon WT), methylisothiazolinone, benzisothiazolin-3-one, 2-octyl-3-isothiazolone, imidacloprid, iodopropynyl butylcarbamate (IPBC), bifenthrin, cypermethrin, permethrin, chitin, chitosan, clorpyrifos, fipronil, carbendazim, cyfluthrin, and 4-alpha-cumylphenol and the particles of the copper compound are distributed within the wood and render the wood resistant to fungal decay.
