The Effect Of pH On Decomposition Of Mylone® (Dazomet) And Tridipam To Fungitoxic Methylisothiocyanate In Wood

J. J. Morrell, C. M. Sexton, S. Lebow


Mylone® and tridipam are two solid chemicals that decompose to produce methylisothiocyanate (MIT), a highly effective wood fumigant. In this study, two techniques—a rapid, test-tube method and a small-scale, wood-block assay—were used to determine the effect of the pH of various chemical buffers on the decomposition of Mylone® and tridipam in Douglas-fir heartwood samples colonized by Poria carbonica. Both chemicals were sensitive to pH, and higher levels of MIT were produced as the pH of the buffers increased. In general, fungal survival was not affected I week after chemical treatment. Complete control of P. carbonica, however, resulted after 4 weeks of exposure to 50 mg Mylone®/block or 150 mg tridipam/block, when each chemical was combined with a pH-12 buffer.

These results suggest that regulating fumigant treatments according to the degree of fungal attack can substantially improve the precision of decay control in wood maintenance programs.


Douglas-fir;wood decay;Poria carbonica;Poria placenta;utility poles;fumigants;Mylone®;tridipam;methylisothiocyanate;pH;buffers

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