If you have unwanted pine trees on your property, you might be wondering, will Roundup kill pines? The short answer is yes, but it’s not the best or most effective method for pine removal. Using a general herbicide like Roundup, which contains glyphosate, on a large, established pine tree is often inneffective and can lead to a long, unsightly death for the tree. This article will guide you through the realities of using herbicides on pines and present better, more reliable alternatives.
Will Roundup Kill Pines
Roundup is a non-selective herbicide, meaning it’s designed to kill most plants it contacts. While it can damage or kill young pine seedlings or saplings with thin bark, mature pine trees are a much tougher challenge. Their thick, corky bark acts like a suit of armor, preventing the herbicide from reaching the vital living tissue underneath. Simply spraying the trunk or foliage of a big pine will rarely, if ever, result in a complete kill.
Why Roundup Falls Short for Pine Removal
Understanding why Roundup is a poor choice helps you avoid wasted time and money. Here are the key reasons:
* Bark Barrier: Mature pine bark is impervious to surface sprays. The glyphosate needs to be absorbed into the sapwood (the tree’s vascular system) to be effective.
* Incomplete Kill: Even if some herbicide is absorbed through wounds or roots, it may only kill sections of the tree. This leaves you with a partially dead, hazardous tree that is still standing.
* Slow and Unpredictable: The process, if it works at all, can take many months. You’re left with a dying tree that can become unstable.
* Root System Survival: Pines often survive by sending up new shoots from the roots if the main trunk is stressed but not fully killed, creating more work for you later.
* Soil Activity: Glyphosate binds tightly to soil particles and does not typically “leach” to kill roots of nearby trees, but accidental overspray can harm desirable plants.
Effective Methods for Killing and Removing Pine Trees
For a permanent solution, you need methods that ensure the tree’s vascular system is comprehensively interrupted. Here are the most effective techniques, listed from most to least recommended for homeowners.
1. Cutting and Treating the Stump (The Most Reliable Method)
This is the standard, professional-recommended method for a reason. It’s fast, effective, and prevents resprouting. You’ll need a chainsaw, a spray bottle or paintbrush, and a concentrated herbicide labeled for stump treatment (often containing triclopyr or a high concentration of glyphosate).
- Cut the Tree Down Safely: Wear proper safety gear. Make a notch cut on the side you want the tree to fall, then a back cut to fell it. Leave a stump as low to the ground as possible.
- Prepare the Herbicide: Mix the stump killer concentrate with water as directed on the label. Pour some into a disposable container.
- Treat the Stump Immediately: Within minutes of cutting, spray or paint the herbicide liberally over the entire surface of the fresh stump. Pay special attention to the outer ring (the cambium layer), as this is where the active transport of sap occurs.
- Cover if Required: Some products instruct you to cover the stump with a plastic bag to prevent rain from washing the chemical away. Check your label.
This method directly injects the herbicide into the tree’s remaining living tissue, transporting it to the roots and ensuring a complete kill.
2. The Hack and Squirt Method (For Standing Trees)
This is effective for killing a standing tree without felling it immediately. It requires a hatchet or chisel and a concentrated herbicide.
- Make the Cuts: Using a hatchet, make downward-angled cuts evenly spaced around the tree’s circumference. Cuts should be about 2 inches apart and deep enough to penetrate the bark into the sapwood.
- Apply the Chemical: Immediately squirt full-strength herbicide into each cut. Be careful not to let it run down the trunk.
- Wait: The tree will die over the next several weeks to months. Once dead, it is much safer and drier to cut down.
3. Basal Bark Treatment (For Smaller Trees)
This works well for pine saplings or trees with a trunk diameter under 6 inches. You use a oil-soluble herbicide (like triclopyr ester) mixed with a penetrating oil.
- Thoroughly spray the lower 12-18 inches of the trunk, completely wetting the bark all the way around.
- The oil carrier helps the herbicide penetrate the bark. This method is best done in late winter or early spring when sap is rising.
What About Killing Pine Tree Roots?
Killing the stump effectively kills the roots. If you’ve already cut a tree down and have a stump resprouting, you can still treat it. Re-cut the stump to expose fresh wood, or drill 1-inch-deep holes around the outer edge and pour stump killer into them. Without foliage, the process relies on this direct application to the cambium layer.
Important Safety and Legal Considerations
Before you take action, keep these critical points in mind:
* Personal Protective Equipment (PPE): Always wear gloves, safety goggles, and long sleeves when handling herbicides.
* Read the Label: It is the law. The label on the herbicide container provides the legal and safe instructions for use, including target plants, mixing rates, and precautions.
* Nearby Plants: Be aware of where the herbicide goes. Root systems of large trees can sometimes graft together, so killing one tree might affect a neighboring tree you want to keep.
* Local Regulations: Check with your local extension office or municipality. Some areas have regulations about tree removal or herbicide use, especially near waterways.
* Professional Help: For large trees, trees near structures, or if you are unsure about safe felling, hiring a licensed arborist or tree removal service is the wisest and safest investment.
Natural Alternatives for Pine Removal
If you prefer to avoid chemicals, your options are more physically demanding but can be effective.
* Stump Grinding: After felling the tree, hire a service to grind the stump below ground level. This removes the resprouting potential but does not kill the roots immediately—they will decay over time.
* Manual Removal: For very small trees, digging out the entire root ball is possible but extremely labor-intensive.
* Smothering the Stump: After cutting the tree low, cover the stump with thick black plastic or a heavy layer of mulch. This can eventually starve the roots of sunlight and oxygen, but it is a very slow process taking years.
FAQ: Common Questions About Killing Pine Trees
Q: What is the fastest way to kill a pine tree?
A: The fastest effective way is to cut it down and immediately treat the fresh stump with a concentrated herbicide. Killing a standing tree will always take weeks for the herbicide to translocate.
Q: Will bleach or salt kill a pine tree?
A: While injecting bleach or rock salt into the soil can damage roots and stress the tree, it is not a reliable or recommended method. It can severely contaminate the soil for years, preventing anything from growing there and posing risks to groundwater.
Q: Can I kill a pine tree without cutting it down?
A: Yes, the “hack and squirt” or basal bark methods described above are designed to kill standing trees. Remember, a dead tree becomes brittle and hazardous, so removal will eventually be necessary.
Q: How long does it take for a pine tree to die after herbicide treatment?
A: With a proper stump treatment, you may see effects in weeks. For hack and squirt on a standing tree, expect foliage to brown and the tree to die over 1-6 months, depending on size and season.
Q: Is it better to grind a stump or kill it with chemicals?
A: Stump grinding gives instant results and removes the physical tripping hazard. Chemical killing is cheaper and less equipment-intensive but leaves the stump in place to decay slowly, which can take many years. Some people do both: kill the stump chemically to prevent resprouting, then grind it later for aesthetics.
Removing a pine tree is a significant task. While the question “will Roundup kill pines” has a technical yes, it’s clear that targeted methods are far superior. For a successful and permanent removal, focus on techniques that directly introduce a suitable herbicide to the tree’s vascular system, like stump treatment or hack and squirt. Always prioritize safety, read product labels carefully, and don’t hesitate to call a professional for large or risky jobs. Making the right choice now will save you time and ensure the job is done correctly the first time.