The causes of Sapstain in Red Beech

Summary

Sapstain in untreated sapwood of red beech (Nothofagus fusca (Hook.f.) Oerst.) from the west coast of South Island was caused by a discolouration of the contents of the wood ray cells followin~ infection by Ceratocystis piceae (Münch) Bakshi. A similar mechanism was mvolved in the staining of borondip treated boards. but there Phialophora fastigiata (Lagerb. and Melin) Conant was the sapstain fungus. An unidentified member of the Sphaeropsidales was the principal fungus isolated from steamed boards where stam was caused by an accumulation of dark pigmented hyphae in the vessels. Laboratory tests confirmed the role of all three fungi in the development of sapstain.

Momentary dipping in a sodium pentachlorophenate-borax solution gave some measure of control. but growth of C. piceae was not completely eliminated. Rapid drying (i.e., forced-air drying) or a dip in a sodium azideborax solution prevented the development of sapstain.