POTENTIAL OF UNMODIFIED AND COPPER-MODIFIED ALKYLAMMONIUM COMPOUNDS AS GROUNDLINE PRESERVATIVES

Pinus radiata D.Don (radiata pine) and Betula alba L. (silver birch) sapwood stakes were exposed for periods of up to 12 months in a fungus cellar after treatment with various unmodified and copper-modified alkylammonium compounds. In general, diaJkyldimethyl ammonium salts performed best, followed by benzalkonium chloride. Primary and tertiary amine salts failed to afford any significant protection from fungal attack. Amendment of treatment solutions with copper salts extended performance of all alkylammonium com-pounds. Results are discussed in conjunction with short-term field trials, and predictions of long-term field performance are attempted. It is concluded that quaternary ammonium compounds, and in particular dialkyldimethyl compounds, show considerable potential for protection of radiata pine in ground contact. This potential is further extended when treated solutions are modified by addition of cupric salts. None of the preservative formulations tested protected silver birch stakes from soft rot, although some performed as well as copper-chrome-arsenate preservative