The effect of nutrient regimes, incubation temperature, media pH, and wood sterilization method on performance of four potential bioprotectants (Pseudomonas putida, Pseudomonas cepacia, Bacillus subtilis, and Trichoderma harzianum) against wood staining fungi were evaluated using small ponderosa pine samples over a four week period. Incubation at 32°C resulted in slight increases in the degree of fungal stain, but the results were not consistent across treatment groups or bioprotectant species. Bioprotectant performance was altered through the use of different media, but, once again, the results were not consistent across all treatments for a given media. The pH of the media had a substantial effect on bioprotectant performance, with acidic conditions producing the poorest performance of bacterial bioprotectants and alkaline conditions reducing the protective effects of Trichoderma harzianum. The method of wood sterilization produced alterations in both the degree of staining and the composition of the microbial flora of the wood. Unsterile samples were stained to a greater degree than either autoclaved or irradiated specimens and the degree of bioprotection was generally lower. Delays in the interval between bioprotectant application and inoculation with wood staining fungi generally reduced the effectiveness of the bioprotectant, suggesting that bioprotection declined with incubation period. The results illustrate the complexity of developing bioprotectants which can effectively compete under the array of conditions common to freshly sawn lumber and suggest that considerable additional research will be necessary to more fully understand the conditions which assure successful protection.

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