Roy asked me this question last night and I had no idea what to answer. We know that there is a toxicity to certain plants from the roots, leaves,hulls, and bark mulches of black walnut trees. What about the ashes? He is burning a lot of walnut slabs from the sawmill and he was not sure if the ashes have this adverse affect also. Anyone have any ideas or knowledge about that? I have posted this on the family board also.