The invention concerns a method and a preservative for protecting wood against decay. According to the method wood is treated with a wood preservative capable of preventing the growth and spread of fungi, said preservative containing at least one complexing agent which binds at least a portion of those metals, typically iron and manganese, naturally occurring in wood that are essential to the growth of fungi. The complexing agents employed can be, e.g., ethylenediaminetetra-acetate, ethylene diamine-di-o-hydroxyphenylacetate a polyphospate or a siderophore produced by a microorganisms. The wood preservative used in the method is water-borne and specific to the decay fungi attacking wood.