There are several ways to safely kill standing trees in order to stop invasive roots fast and pave the way for safe removal later. The best methods are:
- Spray the bottom 12 inches of the bark of the tree with a tree-killing herbicide, such as Tordon.
- Make a series of cuts in the bark around the circumference of the tree and apply a strong herbicide, like Roundup or Tordon.
- Remove a 4–8-inch wide ring of bark around the tree. Apply herbicide to ensure tree roots are killed.
- Drill 1–2 inch deep holes around the circumference of the tree and inject herbicide.
- If the tree is less than 15 feet tall, spray the leaves with foliar herbicide, such as Roundup.
Each of these methods can be used to effectively kill trees down to the root and prevent them from resprouting or sending out new shoots from the roots.
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What is the Best Time of Year to Kill a Tree with Herbicide?
The best time to kill standing trees is in fall. This is because in fall the sap flows downward from the branches to the roots. This means any chemical herbicide applied in fall will naturally be carried to the roots and kill the entire tree.
- Fall is the best time to apply herbicide to standing trees.
- Tree sap flows downward in the fall, carrying herbicide to the roots, which will kill the entire tree.
- Sap flows upward in spring. Herbicide applied at this time will kill leaves and branches but roots will survive.
Spring is not the ideal time to kill standing trees with a herbicide solution. In spring, sap flows upward from the roots. Any herbicide administered through the bark may not reach the roots. This could result in the upper portions of the tree dying while new shoots come up from the roots and base of the trunk.
What is the Best Herbicide for Killing a Tree?
The best herbicide for killing a tree is Tordon RTU. It is formulated to kill trees and brush without harming the grass. It can be used for most tree-killing applications. One thing to note, however, is that Tordon applied to one tree can enter the soil and attack nearby trees, so this option is best used to kill lone trees or clear brushy areas.
- Tordon RTU is a very effective tree killer that won’t harm grass.
- Tordon can enter the soil from the roots of treated trees, damaging nearby trees, so use it with care.
- Roundup can be used to kill trees effectively.
- Roundup will not enter the soil and harm nearby trees and plants, making it safe for use near desirable plants.
Common Roundup compares well to Tordon for tree-killing power. It can be used in a similar manner and has the added benefit of only killing the trees it is applied to. Nearby trees and brush will not be harmed, meaning you can safely kill one tree in a cluster of trees using Roundup.
5 Best Methods for Killing Standing Trees
Basal Bark Treatment
For this method, all you need is a sprayer and Tordon. Spray the bottom 12 inches of bark with Tordon. Essentially, painting a ring of Tordon around the bottom of the tree. The Tordon will soak through the bark and attack the tree, killing it.
- Use a pump sprayer or backpack sprayer to apply Tordon to the bottom 12 inches of bark around the base of the tree.
- Tordon includes a blue dye, to let you know where you have and haven’t sprayed.
- Roundup is not effective for this method—it won’t penetrate tree bark.
You won’t get good results from using Roundup in this way. Glyphosate, the active ingredient in Roundup, is water-based and will evaporate rather than penetrate the bark. You may damage very young, thin-barked trees with Roundup in this way, but it’s unlikely you’ll kill the tree. For this method, Tordon is the best option.
Cut Surface Treatment
The bark of a tree acts as a protective layer. To kill a standing tree, it’s often essential to get past this protection. This cut surface method, also known as “hack and squirt” method is performed by following these steps:
- Use a hatchet or axe to cut downward at angle at a point 6–25 inches (15–64 cm) from the base of the trunk.
- Cut deep enough that the bark peels back and the light, almost white, sapwood of the tree is visible.
- Repeat, making similar cuts every 2–3 inches (5–7.5 cm) around the circumference of the tree.
- Within 10 minutes, thoroughly spray the cuts with Tordon or Roundup.
Because this process exposes the sapwood of the tree, both Tordon and Roundup (or any other Glyphosate product) will be effective as a tree killer. It’s critical to apply the herbicide treatment immediately after making the cuts, to ensure it is absorbed by the tree.
Ringbarking, also known as girdling, is a longstanding method for killing trees and leaving them standing. This is great for killing trees that you will later fell for firewood. However, to make sure you kill both the top of the tree and the tree roots, we recommend the following process:
- Use a hatchet, hammer and chisel, or chainsaw to remove a belt or “girdle” of bark all the way around the tree.
- The ring of removed bark should be 4–8 inches (10–20 cm) wide.
- Immediately apply Tordon or Roundup to the exposed wood where the bark was removed.
Trees transport nutrients just beneath the bark. By removing a ring of bark, you stop the flow of nutrients from the roots to the branches. Although ringbarking without applying herbicide may kill some trees, there is a chance the tree roots will survive. This is why we recommend following it up with application of a herbicide product.
Use a drill and a 1/2 inch (12 mm) drill bit to drill a belt of holes around the base of the tree trunk. Angle the holes downward at 45-degrees. Each hole should be 1 1/2 inches (4 cm) deep. Drill a hole every 2–3 inches around the tree’s circumference. Then, fill the holes with Roundup or Tordon from a sprayer or squeeze bottle applicator.
- Use a power drill and 1/2 inch (12 mm) drill bit.
- Drill holes every 2–3 inches (5–7.5 cm) around the base of the tree.
- Holes should be 1.5 inches (4 cm) deep.
- Drill the holes downward at a 45-degree angle, to allow them to be filled with herbicide.
- Fill the holes with Tordon or Roundup from a sprayer.
This effective method is a lot less messy than the Cut Surface or Ringbarking methods. It delivers the herbicide right into the tree, while the angled holes allow the herbicide to slowly penetrate the sapwood. It reduces the chance that the herbicide will drip off onto soil and nearby plants.
Trees under 15 feet tall can be killed by spraying the foliage with Roundup or a selective weed killer, such as 2,4-D. The bonus of this method is that, unlike the others, it is effective in spring and summer.
- Treat trees under 15 feet tall by spraying the foliage with Roundup or a selective broadleaf weed killer.
- Choose a windless day, so herbicide is not carried onto nearby trees or garden plants.
- This method is best used in spring and summer.
While larger trees will resist this method, if the tree in your yard is small enough, you can kill it with a foliar spray.
What is the Best Way to Kill a Standing Tree?
The best methods for killing a tree without felling it are to spray the base of the tree with Tordon, cut gashes in the tree trunk that are then filled with herbicide, removing a ring of bark around the tree, or drilling holes into the tree trunk before injecting them with herbicide. For trees less than 15 feet tall, you can spray the leaves with Roundup or similar herbicide, which will penetrate to the root and kill the tree.
While there are several reasons to kill a tree and leave it standing, such as stopping growth while you plan safe removal, or killing trees to be felled later for firewood, you should only kill trees that are on your property. Using any of these methods to kill trees that do not belong to you is illegal. Remember to stay safe, wear protective equipment, and you’ll easily get rid of unwanted trees.