Colonization of treated and untreated ponderosa pine exposed in Hilo, Hawaii

IRG/WP 95-20068

C M Freitag, J J Morrell, K J Archer

The rate of decay in above ground exposures is largely controlled by rainfall and temperature, factors which can be used to construct a climate index of decay hazard in above ground exposures. Developers of new biocide formulations have utilized this knowledge by establishing test sites in sub-tropical regions such as the Gulf Coast of the United States. More recently, field sites have been located in regions with even higher climate indices with more severe risks of decay. One such site is Hilo, Hawaii which receives nearly 4000 mm of rainfall per year and has near optimal temperatures for microbial growth. Previous field trials have shown that untreated control L-joints fail in as little as one year at such sites, but the organisms associated with these failures and their interactions in the deterioration process remain poorly understood. It has been suggested that results from such tests may be poor indicators of chemical performance under less severe exposures. To address this issue, the fungal flora colonizing wood was assessed in L-joints and deck boards exposed above ground in Hilo, Hawaii. The samples were either untreated or treated with 0.5% triazole 1, 0.5% tributyltinoxide, 0.5% 3-iodo-2-propynyl butylcarbamate, or 0.25% triazole 2 in mineral spirits or water. Selected samples were removed periodically and cultured for the presence of decay fungi. While basidiomycetes were not prevalent among the initial colonizers, they became increasingly abundant after 18 months of exposure. Among the fungi isolated were Trametes versicolor, Fomitopsis meliae, Schizophyllum commune, and Antrodia sinuosa. These fungi are also found under more temperate exposures suggesting that data from tropical sites represents a similar, albeit more accelerated, progression of decay organisms. Further studies on the decay capabilities of selected isolates are underway.


Keywords: BASIDIOMYCETES; DECAY; WHITE ROT; BROWN ROT; L-JOINTS; DECKING; PINUS PONDEROSA; SOUTHERN PINE; OUT-OF-GROUND CONTACT; COLONIZATION; FUNGI; HAWAII

Conference: 95-05-11/16 Helsingør; Denmark


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