Question
Goodmorning,
Do you know if Sap from a Black Walnut Tree will DAMAGE Treated Wood?  I want to build an Arbor under a Black Walnut Tree in my backyard but my husband says the Sap will damage the wood... Do you know if this is TRUE?

Thank You So Much For Your Help, Michele

Answer
No the sap from a walnut tree will not damage wood. Walnuts do contain a chemical that will kill other plants near the tree. When certain other landscape plants are planted near or under this shade tree they tend to yellow, wilt, and die. This decline occurs because the walnut tree produces a non-toxic, colorless, chemical called hydrojuglone. Hydrojuglone is found in leaves, stems, fruit hulls, inner bark and roots. When exposed to air or soil compounds, hydrojuglone is oxidized into the allelochemical juglone, which is highly toxic.

These toxins will not damage the wood since it is not living cells.