Soil treatment tests with the three products of boric acid for the prevention of the hyphal growth of Serpula lacrymans
S Doi, A Yamada, Y Mineki, M Mori
Laboratory soil treatment tests were conducted for the evaluation of fungicidal or fungistatic effect of boric acid products against Serpula lacrymans. Boric acid products tested were the following three: a thickened boric acid solution in triethanolamine, boric acid-silica gel complex granules, and a nonwoven fabric laminated with a polypropylene film and coated with boric acid granules on one side surface. Effects of these products were evaluated using ezomatsu (Picea jezoensis) wood blocks and Kanuma soil or unsterilized sandy loam as a soil substrate. The thickened boric acid solution exhibited the sufficient efficacy to suppress the hyphal growth and decay of wood with boric acid retention of 2.0 kg/m³ in Kanuma soil medium. The perfect effect of the boric acid-silica gel complex granules was shown with boric acid retention of 3.0 kg/m³. The hyphal growth of the fungus was almost inhibited by placing the nonwoven fabric with boric acid granules over the media incubated with the fungus.