Remedial treatments of CCA-treated poles in service with incipient soft rot were carried out with boron rods, boron/glycol solution, boric acid paste, copper/creosote paste and a commercial product (DFCK paste) respectively. The micro-flora before remedial treatment and 6 months after as well as the spread of chemicals in the poles were reported in Document No: IRG/WP/3388. In this progress report the changes in the micro-flora after 12 and 28 months are detailed together with the results of chemical studies on the spread of borates after 28 months. Studies have also been carried out on the sensitivity to borates of some fungi as well as the soft rot capacity in pine wood of some fungi isolated 28 months after treatment. The results concerning the micro-flora after 28 months are encouraging for boron rods, boron acid paste and especially for DFCK-paste. The spread of borates after 28 months was very good. In sapwood the average concentration, as boric acid, exceeded 2 kg/m³ in treated zones in poles treated with boron rods and 1.0 kg/m³ in treated zones in poles treated with boric acid paste.

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