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Wood Decay Inhibition by Tropical Hardwood Extractives and Related Compounds. Wallace E. Eslyn, Supervisory research plant pathologist, U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, WI 53705; John D. Bultman(2), and Leonard Jurd(3). (2)Research chemist, Environmental Sciences Division, Naval Research Laboratory, Washington, DC 20375; (3)Chief research chemist, USDA Agricultural Research Service, Western Regional Research Laboratory, Berkeley, CA 94170. Phytopathology 71:521-524. Accepted for publication 10 October 1980. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/Phyto-71-521.

Pine blocks were impregnated with the extractives obtusaquinone, obtusastyrene, or lapachol, or with the synthetic compound 2-benzyl-4,6-di-t-butylphenol. The blocks were sterilized by steam or by exposure to ethylene oxide and then subjected to decay by Gloeophyllum trabeum, Poria placenta, or Coriolus versicolor. Obtusastyrene and obtusa quinone were most effective against the brown-rot fungi, controlling them at concentrations of 3 and 3.5%, respectively. Weight losses by C. versicolor were reduced from 23% (steamed blocks) to 4% by a 4% concentration of obtusastyrene and to 6% by a similar concentration of obtusaquinone. Lapachol was effective at its highest concentration (4%) only against P. placenta. Benzylphenol, at a similar concentration, reduced all decay-associated weight losses to 8% or below. Ethylene oxide sterilization resulted in decreased decay by G. trabeum and P. placenta on treated wood. In control (nontreated) wood however, no significant differences in decay susceptibility were detected between blocks sterilized by different methods.