Premature failure of utility poles in Switzerland and Germany related to wood decay basidiomycetes

Abstract

Abstract In contact with soil, copper (Cu) formulations as preservatives are expected to inhibit wood decay by fungi and other soil-borne microorganisms. However, Cu-resistant brown-rot (BR) fungi lead to premature failures of utility poles at some sites. In this study, the service lives of 111 utility poles of Norway spruce (Picea abies (L.) H. Karst) (73 from Switzerland and 38 from Germany) impregnated with Cu-based wood preservatives were investigated. Three segments of each utility pole were analyzed. The severity of decay was dependent on the preservative formulation. BR fungi and in particular Antrodia species were predominantly isolated from utility poles that were not treated with a co-biocide, e.g. boron (B). Cu-sensitivity of several isolated BR fungi was confirmed in studies on Cu-amended medium and in Cu-treated wood. Isolates of Fibroporia vaillantii and Serpula himantioides showed a higher Cu-tolerance than the highly Cu-tolerant Empa isolate Rhodonia placenta (Empa 45) or Antrodia serialis.