Pole sections prepared from seven Canadian wood species (Thuja plicata, Thuja occidentalis, Pinus contorta, Pinus resinosa, Pinus banksiana, Pseudotsuga menziesii, southern yellow pine) were fumigated with chloropicrin, methylisothiocyanate and Vapam and the rates of fumigant penetration determined. All three fumigants were applied directly into holes bored radially into the pole sections. Analysis for fumigants commenced after a few days at various sampling distances from the treating point. After three months the test was concluded. Methylisothiocyanate, diffused equally well upwards or downwards in the pole section from the point of fumigation in all wood species, and appears to offer the best potential of the three fumigants as a pole treatment in Canada. When applied directly, chloropicrin initially moved quickly but then the diffusion rate slowed somewhat. Upward movement was fastest in eastern white and western red cedar while downward movement was also rapid in southern yellow and red pine. Chloropicrin movement was rated as good in Douglas-fir but poor in jack pine. Diffusion of chloropicrin was severely retarded in lodgepole pine. In general Vapam movement was slow at first, and then increased with time. Diffusion rates for all wood species were similar except for relatively rapid upward movement in red and southern yellow pines.