How to Kill Black Locust Trees?

how to kill black locust trees

Black locust leaves, seeds, and thorns are poisonous. So, if they grow on your landscape, you need to immediately get rid of them before they poison other plants and animals. Also, as they grow invasive roots, black locusts can damage the structures around them. In order to prevent these, it is necessary to explore how to kill black locust trees.

Copper poisoning is an easy method that can kill the tree. Also, you can rely on Glyphosate for that matter. But they require proper access to the tree units to work. Let me teach you how to do so!

Should You Cut Down Black Locust Tree On Your Own To Kill It?

Felling a black locust tree is a challenging job. Because the trees grow more than 80 feet. And if you do not have a big and sturdy ladder, you cannot properly access the top limbs to cut them. 

Also, making enough space for them to fall is tough to handle on your own. Hence, you should contact a professional tree removal service

They use tow straps and tie the cut branches. It aids in placing the branches on the ground without damaging any structure nearby.  

How to Kill Black Locust Trees

How to Get Rid of Black Locust Trees?

If you do not get rid of the black locusts, their roots spread far enough to grow dense thickets of locusts. And they affect the health of your beneficial plants. So, to kill either naturally or with chemicals follows the given methods –

Method-1: Use Copper Nails 

Using copper nails is one of the most common natural solutions to kill black locusts. Inserting these nails into the tree trunk can interrupt the flow of nutrients and poison the tree.

And due to copper poisoning and lack of nutrients, the trees die. So, without further ado, follow the steps:

How to Kill Black Locust Trees
  • Get a bunch of copper nails from your local store. You may use old and rusty copper nails but they will not be effective much. 
  • On the lower base of the trunk, insert the nails in a circumference using a hammer. 
  • Keep a half-inch gap between each inserted nail.
  • Push the nails as much as possible so that their pointy ends reach beyond the bark layer.
  • It will take three to five months for the copper nails to kill the tree. 

To know how the copper nails poison the work, give this video a watch:

Method-2: Use Rock Salt and Bleach 

Salt is a necessary nutrient for black locusts until they receive it in moderate amounts. Excessive salt damages their root structures and starve them off. So, to let the salt penetrate the tree, follow the process:

How to Kill Black Locust Trees

Step 1: Preparation 

In a bucket, mix 1:1 rock salt and water. Let the salt absorb the water. Meanwhile, cover the ground around the black locusts with a tarp. It will protect the soil and plants from salt contamination. 

Step 2: Make Drills 

Use a half-inch drill bit to make deep holes around the trunk. There should be an inch gap between all the holes. And ensure the holes face downward at 40 to 45–angles so that they can hold the salt mix without dropping anything. 

Step 3: Apply the Salt 

Insert the salt mix into the holes. Then, spray hot water over the lower trunk. Add a thick layer of straws and twigs as mulch around the tree to retain moisture. 

In order to carry out the task, choose a clear day without any probability of rain. Or else water can wash off the salt before it reaches the roots and branches. 

Step 4: Use Bleach 

The salt mix will decompose the tree in a few months. But until you get rid of the stump, the black locusts can grow back from stump suckers or shoots. So, after a few months, contact a tree felling service to cut down the tree. 

Then, make drills on the stump. And pour bleach into the holes. If possible, cover the stump with plastic sheeting. The bleach will prevent suckers and saplings from growing on the stump.

Method-3: Apply Herbicide 

Natural methods are way too slow at killing black locusts. To speed up the decomposition, you can use herbicide. And the best chemical to kill black locusts is Glyphosate or Tordon. Check out this method:

How to Kill Black Locust Trees

Step 1: Girdle 

Girdling exposes the layer of the bark. Once you girdle and apply herbicide, it kills the locusts faster. So, make a deep cut in the trunk in circumference. 

Below the initial cut, make another cut. With a knife, peel off or remove the layer of bark that is between the two cuts. Then, spray Glyphosate solution on the exposed bark. 

Step 2: Drill the Trunk 

Using a drill, make three to four holes below the girdled or exposed wood of the trunk. The drills should be 0.5 to 1.0 inches deep. While drilling them, maintain a downward angle. 

Then, pour Glyphosate or Tordon into the drilled holes. If you want, you can wrap the holes with aluminum foil to increase the effectiveness of the chemicals. 

Wait for two to three weeks for the chemical to poison the roots. Once the roots die, the tree will die eventually. 


Some yard owners try to replant the black locusts in other areas to get rid of them. But transplanting them around your yard is not a good idea. Because their roots can spread far and invade your properties. So, you must know how to kill black locust trees instead of transplantation.

No matter which method you choose to kill them, avoid doing it while the tree is inactive, especially in the spring.  

You may Also Interested About : How to Kill a Poplar Tree

Frequently Asked Questions (F.A.Q’s):

Can the black locust’s thorns be dangerous?

Yes, black locusts develop clustered thorns that can injure other tender plants and animals nearby. And if the trees grow in density near rivers, the thorns can prevent livestock from accessing the water. 

How long does it take to kill black locusts?

It depends on the method you follow to kill the tree. Usually, the natural methods take at least a few months to start the decomposition, while herbicides can do it in two weeks. 

What is the best herbicide to kill black locusts?

All types of growth regulators can effectively rot and kill black locusts. However, Roundup might not be a good choice for it. Because you need to pour it on the exposed roots for it to work. 

Md Biajid

Meet Mia Biajid, a passionate nature lover. Particularly, he has a deep-rooted connection to the plant. Mia loves to spend time exploring forests and uncovering the secrets held within trees. He always inspires others to appreciate and protect our precious part of the ecosystem.

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