| Summary: | There has been an ongoing debate into the reasons behind the unexpected failure of
alkylammonium compound (AAC) treated wood in field trials. The main objectives of this
thesis were to investigate wood and fungal interactions with AAC wood preservatives, in
order to help answer the question regarding lack of performance.
Fixation studies found that ion exchange plays a minor role in the adsorption of AACs in the
outer regions of the wood. Both fixation and cell wall distribution studies indicated that
AACs preferentially bind onto the lignin. Cellular distribution studies using SEM-EDX
showed that several factors influenced the retention and distribution of AACs. These
included cell type, wood species, sample size, solution pH and treating concentration. The
above work suggests that AAC distribution in the wood has a single weakness. AACs in the
earlywood tracheids are prone to leaching and decline rapidly from the outer surface. These
characteristics would result in areas without protection against invading organisms. Mobility
studies indicated that DDAC depletion in a flooded soil bed study was a combination of both
physical leaching and biological effects.
Bioassay analysis indicated that standard deteriorating fungi were sensitive to AACs. Field
isolations yielded DDAC tolerant Verticillium spp., an Acremonium sp. and Gliocladium
roseum. Further studies found that these tolerant organisms could degrade AACs in a wood
matrix. This highlights an area of concern where the presence of non-decay fungi, could
colonize the AAC-treated wood and may degrade the AACs in the wood to levels inadequate
to control wood decay fungi. === Forestry, Faculty of === Graduate
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