Sodium pentachlorophenol, which was previously found to be the most effective of eight different chemicals tested against blue-stain of timber and recommended at 1 and 2% levels for dipping, has now been further tested in the field. The results show that the chemical effectively controlled the blue-stain infection even at lower concentrations of 0.5 and 0.7%.Botryodiplodia theobromaewas the chief causal agent of infection, although aCeratocystissp. was also present. The chemical at the concentrations used had a repelling action for 4-6 days after application on insect borers (Platypus hintziandXyleborus performa).