Abstract:
ABSTRACT
Fumigants. Chioropicrin, Vapam and Vorlex continue to control Internal
decay of Douglas-fir poles 11 years after application.
Methylisothiocyanate (MIT), which was melted and poured into holes in
Douglas-fir poles 3-years ago and goes directly from a solid to a gas in the
wood, appears promising In controlling decay fungi. Now encapsulated MIT
also appears promising in laboratory tests.
Varying quantities of encapsulated MIT will be placed in decaying
CCA-treated Douglas-fir poles 90 to 100 feet long and in service near
Buffalo, NY. A high percentage of the 81 poles inspected contained decay
fungi; 29 contained decay pockets or carpenter ants.
Cedar sapwood. Twenty 10-foot long pole sections of well weathered
cedar were installed at an OSU test site. Six chemicals, including 10%
penta-chlorophenol in diesel oil will be tested for their ability to control
sapwood decay. Other chemicals have been selected for laboratory
evaluation.
Bolt-hole protection. Twenty-eight Douglas-fir poles 18 feet long were
Boulton dried In a pentachiorophenol-heavy petroleun solution. Eight bolt
holes will be drilled in each pole and the poles will be installed at the
OSU test site. Bolt holes will be protected with preservative powders,
liquids and preservative-containing washers before installation of the
hardware.
Detection of Decay. Chemical color tests, a needle scratch (fracture)
test and radial compression tests were applied to Douglas-fir cores decayed
to weight losses up to 20%. The radial compression test was the most promising
for detecting early decay (weight losses up to 10 percent). A small
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compression testing device for field use has been developed and will be
evaluated.
Extent of decay. In attempts to quantify the extent of early decay in
Douglas-fir and southern pine, small beams and wafers were decayed to weight
losses up to 13%. Large reductions in tnoduli of elasticity and rupture
occurred at small weight losses. A staining technique was developed that
colors undecayed portions of cell walls green and decayed portions orange
when viewed by fluorescent microscopy. Neither computer image analysis nor
alkali solu-bility were satisfactory measures of early decay.
Decay of Douglas-fir Poles Prior to Pressure Treatment. Fourteen
6-inch long cores were removed from about 100 poles at each of 13 air
seasoning yards and the cores were cultured for fungi. Included were
unpeeled poles, freshly peeled poles and poles in various stages of airseasoning.
Cultures are being examined microscopically for Basidiomycetes
which are being isolated, identified, and their ability to decay wood is
being studied.
Research is in progress to deterine how fungi are spread (soil or air)
and how infection of poles occurs.
To determine how and when poles are infected and to follow decay development,
pole sections were placed upright or horizontally at four air
seasoning yards from northern Washington to northern California. Sections
will be removed or replaced periodically during the next 3 years, and the
sections will be extensively sampled by removing cores to determine the
presence of decay fungi.
A 32% water solution of ammonium bifluoride was applied to some horizontal
sections in an attempt to prevent or slow infection of poles.
