Although they’re sought after for their nuts or furniture making, walnut trees (Juglans nigra) release a toxic compound called juglone. They poison the soil and prevent other plants from growing near the walnut tree.
This unfortunate feature and other reasons must have led you to look for ways to get rid of walnut trees. The great news is you’re on the right page, as we can teach you the different ways to do it!
1. Cutting the tree down and treating it with herbicides
| Difficulty | Difficult ●●●●○ |
| Duration | • 1 to 2 hours for spraying the herbicide • 48 hours for complete absorption of the herbicide • 2 to 4 hours for cutting down the tree |
| Things You Need | • Hatchet • Backpack sprayer • Herbicide • Chainsaw |
The first effective way to remove a walnut tree is by cutting it down and treating the remaining stump with herbicides.
This method is best for large walnut trees since they tend to grow between 30 to 140 feet tall. By cutting them down, more than half of the plant dies, and the rest of the stump is dealt with using herbicide.
Here’s a step-by-step guide to doing this.
| How To Do 1. Using a hatchet, make downward cuts along the trunk, exposing its inner flesh or vascular tissues. 2. Spray herbicide into the cuts of the trunk, saturating them completely. 3. Allow the trunk to absorb the herbicide and spread it to its roots for 48 hours. 4. Look for curling or wilting leaves after 48 hours. If you do not see any, make new cuts and repeat spraying of herbicide solution. 5. Using a chainsaw, remove the upper part of the tree by cutting through the trunk from 6 to 12 inches above the ground. 6. Create a V-shaped cut several inches going in the tree. The undercut must be at least ⅓ of the trunk’s thickness. 7. Go to the opposite side and make a straight cut at the same height as the undercut. 8. As you finish the straight cut, the tree will fall. Keep a safe distance away from the falling tree. 9. Spray the top of the remaining tree stump with herbicide. 10. Repeat spraying every two days for one week or until the flesh turns gray. |
2. Ring barking
| Difficulty | Average ●●●○○ |
| Duration | 2 to 3 hours |
| Things You Need | • Hatchet • Backpack sprayer • Herbicide |
Ring barking or girdling involves removing a strip of the bark and letting the chemical enter the tree’s vascular system to kill the tree and its roots altogether. Here’s how to apply the ring barking method to remove your walnut tree
| How To Do 1. Using a hatchet, cut a ring through the bark of the walnut tree, about 4 feet above the ground. The ring should be 2 inches wide and deep. 2. Cut a second ring about 4 inches above the first ring. 3. Spray the exposed girdling marks of the trunk with herbicide. 4. Cut down the walnut tree after the bark has turned gray and the leaves have turned brown and wilted. |
3. Foliar spraying
| Difficulty | Easy ●○○○○ |
| Duration | 1 to 2 hours |
| Things You Need | • Protective gear • Backpack sprayer • Herbicide • Dye |
The foliar spray method is best applied during spring when the walnut tree has the most leaves.
This method involves spraying herbicide on the walnut tree leaves as an entryway for the toxic chemicals to get to the tree’s roots. Once they reach the roots, they will disrupt the plant’s nutrient flow and will slowly starve the tree to death.
Here are steps on how to do the foliar method on walnut trees.
| How To Do 1. Add a few drops of dye to your chosen herbicide. This will later guide you to know what part of the walnut has been treated. 2. Wear protective gear to prevent the herbicide from coming into contact with your skin. 3. Pour herbicide into the backpack sprayer. 4. Spray the herbicide on the leaves of the walnut tree. |
4. Basal bark treatment
| Difficulty | Easy ●○○○○ |
| Duration | • 30 minutes to 1 hour per day • Apply every other day for one week |
| Things You Need | • Backpack sprayer • Herbicide • Oil-based solvent • Metal container |
With basal bark treatment, the herbicide is spread on the bottom 20 inches of the walnut tree. This ensures the absorption of its roots of the chemicals that will fast-track the damage and disruption of the plant’s vascular system.
Without the necessary nutrients, the walnut tree cannot make its food via photosynthesis, causing it to die gradually. Here’s how to apply the basal bark treatment to your tree.
| How To Do 1. Mix 1-part herbicide and 4-part solvent in a container to achieve a 20 to 25% concentration. 2. Make sure that the tree is dry before spraying the solution. Otherwise, the hydrophobic oil-based solvent will prevent absorption. 3. Spray the solution on the bottom 20 inches of the walnut tree. Let it dry. 4. After the first layer has been fully absorbed, spray another layer to ensure the effectiveness of the herbicide on the walnut tree. |
5. Cut surface treatment
| Difficulty | Average ●●●○○ |
| Duration | 1 to 2 hours |
| Things You Need | • Hatchet or axe • Herbicide |
The cut surface treatment is another way to expose the vascular cambium of the tree. By making deep gashes around the tree’s bark, the inner flesh is exposed to the herbicide.
As soon as the herbicide enters the tree’s vascular and root system, it will disrupt the flow of nutrients and slowly kill the walnut tree. Here are the steps on how to do the cut surface treatment.
| How To Do 1. Make deep gashes as deep as 3 inches around the tree’s bark using a hatchet. The cuts may be straight, diagonal or in a hashtag (#) pattern. 2. Spray herbicide on the deep gashes until the tree absorbs the herbicide solution. |
6. Chemical injection
| Difficulty | Easy ●○○○○ |
| Duration | 30 minutes to 1 hour |
| Things You Need | • Drill • Herbicide |
With the chemical injection method, you’ll more directly apply the herbicide into the xylem tissue of the walnut tree. The chemical injection method is best done during early spring since the tree’s nutrient flow is most active.
As the herbicide spreads, the walnut tree cannot conduct photosynthesis and absorb more nutrients causing its death.
Below are steps to do the chemical injection method for walnut trees.
| How To Do 1. Measure the tree 2 to 3 feet above the ground. 2. From there, drill 2 to 3-inch-deep holes around the tree’s circumference at a downward angle. 3. Inject or fill the holes with herbicide and wait for it to be fully absorbed. Repeat this step twice to increase absorption. 4. If the tree has multiple trunks, you can drill holes and fill them with herbicide to speed up the tree’s death. |
What is the best way to kill a walnut tree based on size?
The basal bark treatment is the most effective way to kill small walnut trees, while the chemical injection method is the best way to kill large walnut trees.
| Size | Effective Removal Method |
| Small (less than 10 feet tall or less than 7 inches in diameter) | • Basal Bark Treatment • Herbicide is applied directly onto the tree’s roots and kills its main source of nutrients almost instantly. |
| Large (more than 10 feet tall or 8 inches and above in diameter) | • Chemical Injection Method • Herbicide is absorbed more directly through the inner flesh of the bark and in higher quantities which speeds up the disruption of nutrient flow in the tree. |
FAQs
The best time to kill a walnut tree is from winter to early spring, so the tree will be deprived of nutrients to grow new leaves and seeds in spring.
Walnut trees die within 14 days to 6 months after being treated with herbicide, depending on the size and method used to kill the tree.
Salt can only effectively kill small walnut trees. Salt can stop the flow of potassium and magnesium inside the tree, killing its root system.
You can kill a walnut tree without cutting it down. Effective methods include ring barking, foliar spray, basal bark or cut surface treatment.
You can spray herbicides that have glyphosate to effectively kill walnut trees. They prevent plants from making proteins for their growth and send nutrients to their leaves, stems, and branches.
Remove the entire taproot of the plant manually or using a stump grinder. You can also coat the remaining walnut tree stump with herbicide.
