The effect of stack height on the performance of preservatives used for the prevention of sapstain on seasoning wood
J R Williams, D J Dickinson, J F Webber
The performance of three anti-sapstain preservatives was investigated under field conditions in south east England. The preservatives under test were: copper-8-quinolinolate (Mitrol PQ8) trimethylalkylammoniumchloride and sodium hexanoate (Sinesto B) and chlorothalonil (Tuff Brite). The preservatives were tested on Corsican Pine grown in south east England. The field trial was set up to investigate the robustness of the field trial protocol laid down as part of a collaborative European research project. Treated boards were close stacked and were assessed at 12, 18 and 24 week intervals. The test preservatives varied in efficacy: copper-8-quinolinolate (Cu-8) performed better than the quaternary ammonium compound (Quat) and chlorothalonil. However, very little mould colonisation occurred on the chlorothalonil treated boards compared with the boards treated with the other anti-sapstain preservatives. Observations also indicated that mould fungi were more prevalent on the upper boards of the top packs and that sapstain was heaviest on the bottom boards of the packs for all treatments. The results clearly showed that the height of the stacks had an effect on the infection pathways of colonising fungi and timber closer to ground level was clearly exposed to the greatest hazard. Statistical analysis supported this observation. Comparative field trials assessing antisapstain preservative performance should be set with the test stacks in a single layer at ground level.