Potential for Using Borates to Mitigate the Risk of Phytophthora ramorum Spread on Douglas-Fir Logs

Phytophthora ramorum is an increasingly important tree pathogen in northern California and southern Oregon. While it has the greatest effect on tanoak, it can infect a wide range of tree species, including Douglas-fir. Oregon has instituted a quarantine area to slow the spread of this pathogen, and there are concerns that further restrictions may be imposed on log movement, including those of Douglas-fir. The potential for using boron as a log treatment to limit P. ramorum was evaluated. While boron either alone or in a glycol solution was capable of moving into the bark, there was no evidence that it could move further into the sapwood. The results suggest that bark removal would be necessary for the use of boron as a mitigation agent for the spread of P. ramorum.