Perkins from Ks writes
Tordon RTU Spray is not labeled for Walnut Trees therefore we cannot confirm if it would be effective in killing the tree. Black Walnut tree roots can spread out 50-80ft from the tree and are known for resprouting. The most recommended treatment is to cut the stump as low to the ground as possible and apply a product with the active ingredient Glyphosate directly to the freshly cut stump. Direct stump treatments is going to be your best option and will take several months and maybe longer since this tree is so old. Roundup QuickPRO has Diquat as 1 of the 2 ingredients works for a faster knockdown and absorbs throughout the root system better. Drilling into the stump is also sometimes done for the herbcide to absorb quicker into the tree.
Answer last updated on: 10/14/2022
