How to Kill Oak Trees

How to Kill Oak Trees

In many cultures, the oak tree is a symbol of strength, perseverance, and knowledge. Able to live to a few thousand years, they’re one of the longest-living trees on Earth. 

But despite how majestic they can look, they can be quite a nuisance when in unwanted places. 

Whether they’re destroying structural foundations or simply ruining your landscape’s appearance, we’ve listed several ways you can kill your oak tree without cutting it down. 

1. Foliar Spraying

Foliar Spraying
DifficultyEasy ●●○○○
SpeedFast-acting
Things You Need• Personal protective equipment

• Backpack sprayer or spray bottle

• Systemic herbicide

• Dye (optional)

Applying foliar spray is exactly how it sounds – spraying the leaves of your oak tree with triclopyr or glyphosate-based herbicide. See? It’s pretty straightforward and actually one of the easiest methods on this list. 

In fact, the foliar spray method works great if you have a reasonably-sized oak tree with a ton of foliage. Because of its many leaves, there will be several entry points for the herbicide to penetrate through and reach the inner layers of the tree. 

The key to ensuring that this technique is flawless is by using systemic herbicides such as glyphosate, triclopyr, and 2,4-D. The reason for this is that systemic herbicides are more effective as they work from the inside out. 

If your oak tree is situated near vegetative crops or other plants that you don’t want getting harmed, we recommend using triclopyr or 2,4-D. These are systemic herbicides which means that they only work on woody and broadleaf plants.

How To Kill an Oak Tree with Foliar Spray
1. Prepare your herbicide according to the label’s instructions. 
Preparing your herbicide for application will depend on the type you have. 
Certain kinds of herbicides require preparatory steps such as diluting in water. Meanwhile, others are ready for use immediately out of the package.
Hence, read the label’s instructions thoroughly so you’ll know how to proceed. 
Other than that, we recommend adding dye to your herbicide because this allows you to easily identify which areas you’ve applied herbicide to.
2. Spray the top of your oak tree’s canopy, carefully moving downwards from left to right (or vice-versa).
From the topmost part of your oak tree’s canopy, slowly move your sprayer downwards from left to right (or vice-versa depending on which side you started).
Keeping your application cohesive and organized ensures that each leaf is evenly coated. This also reduces the amount of herbicide wastage.
Remember to not be too generous with your application either. You’ll want thorough coverage, not leaves that have herbicide dripping from them.
3. Monitor your oak tree for signs of deterioration.
After your application, the next step is simply waiting for the herbicide to kick in and do its job. This includes keeping a close eye on your oak tree for signs that its health is deteriorating.
You should look for:
• Discolored foliage, typically yellow or brown
• Distorted foliage, usually curled upwards like a bowl
• Wilted leaves
• Sparse foliage
• Stunted growth
• Dropped and fragile branches
If you don’t notice any of these, you’ll need to reapply your herbicide. Afterward, continue to monitor for any signs of decline. 
Should your oak tree remain unfazed by this, you may want to raise the concentration levels of your herbicide and reapply again. 
4. After your oak tree has died, you can remove it. 
For this step, hiring an arborist ensures that your oak tree is removed completely, leaving no roots. Alternatively, you can do this yourself with the right equipment.

Planter’s Tip:

To get the most out of your herbicide of choice, we suggest spraying your foliage on a clear and sunny day. When the leaves are dry, the herbicide adheres better to the surface.

2. Girdling or Ring Barking 

Girdling or Ring Barking 
DifficultyModerate – Hard ●●●●○
SpeedSlow-acting
Things You Need• Personal protective equipment

• Herbicide (optional)

• Ax, hatchet, or chainsaw

• Sharp chisel-type tool

• Dye (optional)

If you’re going for the au naturale route, then girdling or ring barking is an effective way to kill your oak tree without the use of any chemical herbicides.

Just as it sounds, all you need to do to perform this old-school method is to remove several layers from the tree’s stem. Don’t be fooled, though, because this is quite a lot of work. 

But here’s the hitch: girdling or ring barking alone isn’t a fast-acting method. In fact, it could take half a year or more before your tree dies.

Having said that, you can apply chemical herbicide onto the freshly girdled area to hasten the deterioration process, especially if you have a large oak tree. 

How To Kill an Oak Tree by Girdling or Ring Barking
1. Using a sharp tool, make a 45-degree angled cut downwards around the circumference of the tree. 
2. With the same tool, cut around the circumference of your tree about 4 to 8 inches apart from the previous one. 
3. Now that you have an outline, begin hacking away at the portion of the trunk in between the two lines that you made.
Refrain from making haphazard cuts as this is dangerous and could make you more prone to injuring yourself. Instead, take your time at making cuts at the bark as it’ll be difficult to chip away its thick layers.
4. After you’ve girdled your tree, you can let it be or douse a generous layer of chemical herbicide into the recently exposed area.
5. Monitor your oak tree for signs of deterioration.
After your application, the next step is simply waiting for the herbicide to kick in and do its job. This includes keeping a close eye on your oak tree for signs that its health is deteriorating.
You should look for:
• Discolored foliage, typically yellow or brown
• Distorted foliage, usually curled upwards like a bowl
• Wilted leaves
• Sparse foliage
• Stunted growth
• Dropped and fragile branches
If you don’t notice any of these, you’ll need to reapply your herbicide. Afterward, continue to monitor for any signs of decline. 
Should your oak tree remain unfazed by this, you may want to raise the concentration levels of your herbicide and reapply again. 
6. After your oak tree has died, you can remove it. 
For this step, hiring an arborist ensures that your oak tree is removed completely, leaving no roots. Alternatively, you can do this yourself with the right equipment.

Planter’s Tip:

To get the deed done quicker, we recommend using a shark ax or hatchet. Alternatively, you could use a chainsaw, too, depending on your preference. 

3. Administering Basal Bark Treatment

Administering Basal Bark Treatment
DifficultyEasy ●●○○○
SpeedFast-acting
Things You Need• Backpack sprayer or spray bottle

• Triclopyr-based herbicide

• Dye or colorant (optional)

As the name suggests, the basal bark technique involves spraying the base of your oak tree’s bark with herbicide. So if you have grazing animals on your property, we suggest trying out the other methods on this list. 

If you checked out the previously mentioned methods, you’ll notice that this technique is similar to the foliar spray technique. The only difference is the location where you’ll be applying the herbicide. 

The foliar spray technique works well for bushy plants with thin barks and stems no bigger than 6 inches in diameter. So if your oak tree doesn’t meet these standards, your next bet is doing the basal bark technique. 

How To Kill an Oak Tree with the Basal Bark Treatment
1. First things first, prepare your triclopyr-based herbicide as directed by the packaging’s instructions. 
Keep in mind that the preparatory steps required for your herbicide will depend on what kind you picked up from the store. Hence, it’s important to read through the instructions first.
Afterward, we suggest adding a colorant or dye so that any areas that have been treated will be easily distinguishable. 
2. Then, spray a generous amount onto the bottom half of your oak tree’s bark – about 12 to 15 inches from the ground. 
Remember to apply a thin and even coating. You don’t want to overdo it as the excess herbicide will simply drip and collect onto the soil.
This could potentially be harmful to nearby plants that are susceptible to triclopyr.
3. After application, monitor your oak tree for any signs of deterioration that could signal that your application was effective.
To know that your oak tree has been negatively affected by the basal bark treatment, you should be able to notice the following:
• Discolored leaves that are usually yellow or brown
• Wilted, distorted, or curled leaves
• Sparse canopy
• Stopped growth
• Drooped branches
4. Reapply the triclopyr-based herbicide if your tree hasn’t shown any signs of deterioration within a couple of months. 
5. Once your oak tree has died, you can either remove it yourself or by a professional arborist. 

Planter’s Tip:

To ensure effectiveness, we suggest using a triclopyr herbicide (row 51) since it’s the ideal herbicide for treating woody-stemmed plants. 

To easily spot which areas you’ve already treated, especially if you’ve got a ton of oak trees to do, we advise adding a bright dye or colorant to your herbicide. 

4. Injecting the Tree with Chemicals

Injecting the Tree with Chemicals
Image: C&EN
DifficultyModerate ●●●○○
SpeedFast-acting
Things You Need• Personal protective equipment

• Tree injector or power drill

• Glyphosate or triclopyr-based herbicide

• Heavy-duty plastic

Injecting a tree with a chemical herbicide is as straightforward as it gets. So, you don’t have to worry about a ton of steps or preparing lots of equipment.

In fact, all you need is a high-quality tree injector that’ll penetrate through several layers of your oak tree’s trunk. 

Alternatively, you can make do with a power drill. Just be sure to drill a hole at an angle, about 40-degrees, so that the herbicide collects in the tree without spilling out. 

How To Kill Oak Trees with Chemical Injections
1. Plan the areas where you want to inject or drill holes in.
2. If you’re using an injection, fill it in with your herbicide of choice and inject deeply into the tree.
If you’re using a power drill, create a 45-degree angled hole into the trunk of the tree. 
3. Once you’ve got your hole, fill it in with herbicide. 
4. Afterwards, cover the hole with a heavy-duty plastic.
5. Next, monitor your oak tree for any signs of deterioration that could signal that your application was effective.
To know that your oak tree has been negatively affected by the basal bark treatment, you should be able to notice the following:
• Discolored leaves that are usually yellow or brown
• Wilted, distorted, or curled leaves
• Sparse canopy
• Stopped growth
• Drooped branches
6. Redo the treatment if your tree hasn’t shown any signs of deterioration within a couple of months. 
7. Once your oak tree has died, you can either remove it yourself or by a professional arborist. 

Planter’s Tip:

To boost effectiveness, we recommend injecting in several areas all over the tree. You can space them a few inches apart from one another.

5. Performing the Cut Surface Treatment

Performing the Cut Surface Treatment
DifficultyHard ●●●●●
SpeedSlow-acting
Things You Need• Personal protective equipment

• Glyphosate or picloram-based herbicide

• Dye

• Hatchet

• Heavy-duty plastic sheet

If you don’t have a tree injector or a power drill, performing the cut surface treatment is the next best thing. 

Similar to the aforementioned methods, the cut surface treatment requires creating several angled incisions on your oak tree’s trunk then applying a chemical herbicide. 

The idea is that the incision will make it easier for the herbicide to penetrate the tree, ultimately killing it quicker. 

This method is also sometimes called the “hack-and-squirt technique” because it involves literally hacking away at the trunk and squirting a generous amount of herbicide onto the tree’s wound.

How To Kill an Oak Tree with the Cut Surface Treatment
1. Prepare your chemical herbicide for application.
It’s worth highlighting that some chemical herbicides require preparatory steps before application. Some varieties require dilution while others come in a ready-made formula. 
Hence, it’s vital that you read the label properly to ensure that you’re picking up the correct variant. 
While optional, we also encourage using a bottle with a squeeze-top for easier application. This way, you’re given more control. 
2. Next, make several downward hacks around the circumference of your oak tree.
Your cuts should be made at a 45-degree angle to ensure that some of the chemical herbicide stays . 
If you’d like to add more strength to this technique, you can make several 2 to 7-inch holes at a 45-degree angle, too. That’ll be combining the hack-and-squirt technique along with the injecting method.
3. After you’ve made your incisions, apply a generous amount of chemical herbicide onto the hole or cut.
4. Protect the hole or cut by covering it with a heavy-duty plastic.
Putting a plastic cover over the hole or cut protects it from the elements which could dilute its potency and reduce its effectiveness.
5. Keep an eye on the progress by monitoring  for any signs of deterioration that could signal that your application was effective.
To know that your oak tree has been negatively affected by the basal bark treatment, you should be able to notice the following:
• Discolored leaves that are usually yellow or brown
• Wilted, distorted, or curled leaves
• Sparse canopy
• Stopped growth
• Drooped branches
6. If your oak tree seems to be putting up quite a fight, reapply as necessary.
Check to see whether your incisions were deep enough or if your chemical herbicide is strong enough.
If your oak tree doesn’t show any signs of decline, you may want to create deeper incisions or use a stronger chemical herbicide.
7. Once your oak tree has died, you can either remove it yourself or by a professional arborist. 

Planter’s Tip:

To boost effectiveness, your cut should be made at an angle so that the herbicide doesn’t simply dry up or drip away. 

6. Inducing Salt Stress

 Inducing Salt Stress
DifficultyModerate ●●●○○
SpeedSlow-acting
Things You Need• Chainsaw

• Pruning shears

• Power drill

• Rock or Epsom salt

• Water

• Heavy-duty plastic sheet

• Funnel (optional)

Salt works wonders in the culinary world, but did you know that it serves a purpose in the gardening world, too?

A cheaper alternative to chemical herbicides, using salt is a slow-acting poison that’ll have your oak tree wither within several months to a few years depending on the size of your tree. 

We do have to warn you, though, that this method is quite tedious. So if you’re not willing to render in the time, then we suggest choosing through the other techniques on this list. 

How To Kill an Oak Tree with Salt
1. With a power drill, puncture holes several inches deep all over the base of your oak tree.
For extra measure, drill holes a few inches apart from one another. You can also add holes in surface roots.
2. Add a heap of salt inside each hole. 
3. Pour in a cup or two of water. 
Mixing in water will aid in diluting the salt, making it easier to absorb. However, be careful not to overdo it or the salt mixture won’t be as potent. 
4. To protect the holes from drying out or getting diluted from the rain, cover them with a heavy-duty plastic cover.
5. Keep an eye on the progress by monitoring  for any signs of deterioration that could signal that your application was effective.
To know that your oak tree has been negatively affected by the basal bark treatment, you should be able to notice the following:
• Discolored leaves that are usually yellow or brown
• Wilted, distorted, or curled leaves
• Sparse canopy
• Stopped growth
• Drooped branches
6. Inspect your holes and add more salt or water if necessary.
As mentioned earlier, this method takes a while to take effect so you’ll need to be diligent in replenishing the holes with your saltwater mixture. 
7. Once your oak tree has died, you can either remove it yourself or by a professional arborist. 

Planter’s Tip:

We highly encourage moving away plants that are susceptible to dying along with testing out your soil’s pH level to be able to remedy any imbalances that could occur. 

7. Hiring an Arborist

Hiring an Arborist

While you will have to shell out a bit of cash, getting a professional to get the job done will surely save you a ton of time and effort. 

Aside from that, getting the pros ensures that the task is done right. They’ve got all the experience, tools, and equipment to ensure that your oak tree is removed safely. 

This is definitely your best bet if you’ve got an oak tree that can’t be easily removed because of nearby infrastructure. 

FAQs

Are oak tree roots destructive?


Oak tree roots can become destructive overtime as they grow bigger and become invasive. With their far-reaching roots, they can cause structural damage to nearby infrastructures.

Can I use logs from an oak tree as firewood?


You can use logs from an oak tree as firewood, thanks to their ability to retain a consistently low flame. As a result, they’re a good choice for those who don’t want to tend to their fire as much.

But here’s the hitch: you’ll need to ensure that your oak wood log is properly seasoned. Otherwise, too much moisture will result in a lot of smoke when burning.

Can I not remove my dead oak tree?


It isn’t recommended to leave dead trees in the ground because they’ll continue to deteriorate and weaken over time. 

The larger your tree is, the bigger the risk of it falling over. This could cause unwanted accidents and damage, which is why it’s best to remove it as soon as possible.

Why are oak trees difficult to kill?


Oak trees are difficult to kill because they grow branches from their stem as a survival mechanism. To avoid this, you’ll want to kill the entire plant and remove every trace of its roots.

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