What is Roundup and Will It Kill Pine Trees?

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Roundup is one of the most widely used herbicides for killing unwanted plants and trees. It is known for its versatility and effectiveness on a wide range of plants and trees. Pine trees are some of the most abundant tree species in the world, and a lot of people have to wonder whether Roundup can be used to kill Pines or not.

Let’s take a look at whether you can use Roundup on Pine trees and how to use the herbicide correctly for the best results.

Even though roundup is most effective if directly applied to the foliage, regular use of roundup around wanted trees like pine, can harm and eventually kill it. On the other hand, If you want to kill a pine using roundup, it has to be delivered directly to its vascular system to be effective

What Is Roundup?

Roundup is one of the most widely used herbicides all over the US, it is majorly used for controlling the growth of invasive and unwanted weed and tree species. The major ingredient in Roundup is known as Glyphosate and its effectiveness can be seen within a few hours after application. A tree can die within a couple of weeks of applying Roundup.

How Does It Work?

The active ingredient in Roundup is called Glyphosate and it is systemic in nature. This means that the chemical will be absorbed by the tree and travel throughout its vascular system to target the roots of the tree.

Glyphosate targets and inhibits a specific enzyme within the tree called EPSP Synthase. This enzyme is responsible for regulating the production of essential proteins which a plant needs for growth.

One of the first signs of Roundup being effective can be seen through the color of the leaves. The leaves will turn dark yellow or brown and eventually fall off. The plant will slowly die over the span of a couple of weeks.

Is Roundup Able to Kill Pine Trees?

Roundup or Glyphosate is effective for killing Pine trees if applied correctly. It is especially effective on smaller Pine trees as its foliage is easily accessible by herbicide sprayers. Roundup is the most effective when it is sprayed directly on the leaves.

Even though Roundup is effective on Pine trees, it won’t work as well if you simply spray it on the bark of the tree, as this will reduce its absorption efficiency.

To kill bigger Pine trees than a few feet, Roundup has to be delivered directly into the vascular system of the pine by using Chemical Injection Method or Cut Surface Treatment.

I have another article discussing How To Kill a Pine tree

What Equipment Will You Need to Use Roundup?

Along with Roundup, the only other thing you will need is a portable sprayer or a backpack sprayer. This is going to be used as a delivery method for the herbicide. If you only have to kill a few trees, then you should use a comfort wand (Amazon affiliate link) version of the herbicide. It is a small, portable spraying device that will give you a continuous herbicide spray without any of the additional equipment.

How to Use Roundup Correctly?

One of the best features about Roundup is its ease of use, you don’t have to mix it with anything and it can be used straight out of the container. Just fill the sprayer with the herbicide and you are good to go.

If the Pine tree is small and the sprayer can reach its foliage, spray the herbicide to entirely cover the foliage from all angles. Make sure that there is no water, snow, or frost on the leaves of the tree while spraying the chemical.

If the leaves are covered with water or frost, it will reduce their absorption efficiency and will lead to a decrease in ineffectiveness.

If the Pine tree is bigger than a few feet, you should use Cut Surface Treatment to increase the absorption rate.

Using an ax, slash deep gashes into the bark of the pine tree, around the entire circumference, and Spray Roundup into the exposed area. This way the chemical can bypass the bark, straight into the cambium layer of the tree, and directly reach its vascular system.

You can also cut down the tree and treat the remaining stump with Roundup to ensure that the entire root system of the tree dies.

How Long Does Roundup Stay Active in The Soil?

A United States Department of Agriculture’s paper states that Glyphosate has a half-life between a couple of days to 249 days. This indicates that Roundup can remain active in the soil for quite some time. Although different studies have come up with slightly different time frames, most of them also indicate that even though the chemical can be active for a long time, it becomes harmless towards other vegetation rather quickly.

How Can You Protect Plants Which Have Been Accidentally Exposed to Roundup?

You don’t need to panic if some wanted plants or trees have been accidentally sprayed with Roundup as It takes up to 30 minutes for the chemical to be fully absorbed.

As soon the plant comes in contact with the herbicide, wash it down with water. The herbicide can easily be washed away if done right away as it is quite susceptible to water.

Alternatively, you can also use soil, ammonia, or bleach to neutralize the chemical and reduce its effectiveness.


Pine trees are susceptible to Roundup or Glyphosate. To kill a small Pine using Roundup, cover the entire foliage of the tree with the herbicide for the most effective results. Alternatively, you can also use the chemical injection method for larger trees to deliver the herbicide directly into Pines vascular system.

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