STUMP PROTECTION AGAINST FOMES ANNOSUS I. TREATMENT WITH CREOSOTE

Creosoting of pine stumps immediately after felling commonly prevents the entry of Fomes annosus and other primary basidiomycete colonizers through the cut surface. Ceratocystis spp. and Ophionectria cylindrospora frequently enter creosoted stumps, but growth tends to be slow. Light applications of creosote often fail to exclude basidiomycetes. Failure to achieve protection may also result from delay in application, especially when resin flow from the cut surface is rapid; this flow impedes creosote penetration. In one experiment creosoting also controlled air-borne Fomes annosus infection of larch stumps. Various protectants were tested in the forest, a preliminary indication of their efficiency being obtainable after 2 months. A gasworks creosote (B.P. 190-300 degrees C.) was promising, whilst a tar/creosote mixture was unsatisfactory. Disadvantages of creosote as a stump protectant arise mainly from its retarding effect on stump colonization. Creosoted stumps tend to remain alive longer than untreated ones and the risk of F. annosus attaining dominance in stumps already having root infection is correspondingly greater.