Question
Hi, we are doing some serious retaining walls on our property in Oakland. We live on a steep lot, and this tree is at the top, at the road level. About 8 feet downslope (in the critical root zone?) there is a 3 inch root we would like to remove. There are other nearby much thicker roots we do not plan to disturb. Do you believe that cutting this one root would affect the tree's health or stability? Also, is there a product that would be worth putting on the root to prevent future growth?

Answer
Cutting one root should not damage the tree. It will not effect the stability. There are not any products that prevent root growth that will not harm the tree. If you are concerned about the wall put a root barrier along the wall between the tree and the wall and this will stop the roots from getting to the wall.