The effect of different concentrations of polesaver rods on the survival of selected decay fungi in liquid culture
M A Powell, T Deldot, C McEvoy
An in-vitro method was developed to determine the effect of solutions of Polesaver Rods on the survival of selected decay fungi. Polesaver Rods are a diffusing preservative treatment containing fluorine and boron designed for the internal remedial treatment of power poles.
Two white-rot fungi, Perenniporia tephropora and Trametes versicolor, and two brown-rot fungi, Polyporus verecundus and Gloeophyllum abietinum, were grown in flasks of liquid growth media containing one of eight different concentrations of Polesaver Rods. Subcultures were made from the mycelium in the flasks after 1 day, 1, 2, 4 and 8 weeks exposure. Sampled mycelium was inoculated onto a malt agar medium and emergent fungi were identified to determine survival of the original inoculum. Media aliquots were taken at each sample time for confirmatory analysis of boron and fluorine concentrations as well as the determination of residual glucose.
All four test fungi exhibited increasing susceptibility to the Polesaver Rod solutions with time. Exposure for one week to the highest concentration (1.6% Polesaver Rod) was sufficient to kill all test fungi. Three of the fungi survived 2 weeks exposure to a 0.4% Polesaver Rod solution. After 8 weeks exposure to this concentration only one of the test fungi that was selected in this experiment for its known tolerance to boron, Polyporus verecundus, was able to survive.