Methods of inoculating Acer spp., Populus tremuloides, and Fagus grandifolia logs for commercial spalting applications

One of the most promising wood value-added processes currently under development is spalting, where pigment is added to wood via fungal colonization. Previous studies have shown laboratory level spalting to be achievable and highly predictable. However, large-scale spalting for potential commercial applications introduces a substantial number of additional variables which impact the spalting process. To test the potential of commercial-scale spalting, Acer saccharum, Fagus grandifolia, and Populus tremuloides logs were inoculated with multiple known spalting fungi utilizing both liquid spray cultures and live dowel pin cultures. Many of the fungi that successfully produce spalting in small, sterile cultures also produced significant amounts in large logs, with many spalting patterns identical to those found in small-scale testing. Pairings of Trametes versicolor/Scytalidium cuboideum and Xylaria polymorpha/Xylaria polymorpha (different isolates) produced significant amounts of zone lines. In addition, the method of inoculation impacted the amount of spalting: more zone lines were produced when fungi were introduced via plugs, while more stain was produced when liquid cultures were sprayed onto the logs. These results indicate that many of the standard spalting fungi are suitable for large-scale applications; however, the inoculation method appears to be a vital component for successful spalting under a restricted time schedule.