John in NM
Or fungus? I'm not up on the microbe taxonomy.
This is a well studied area, boric acid dissolved in boiling water and mixed 50+50 with glycol is the recipe I remember finding. Soak in as Barry describes. It works as well as the nastier PT chemicals, but the downside is that it is water soluble, so it's not permanent enough for commercial PT operations.
Probably won't last forever, but it will beat what you got with untreated wood.