How to Kill Poison Oak

Published November 7, 2019
Poison Oak

You can learn how to kill invasive poison oak by using one of the many methods. Herbicides are often used, but organic methods aren't as harsh to the environment.

How to Identify Poison Oak Characteristics

Before you set out to kill poison oak, you need to know how to identify it. Poison oak has some similar traits as poison ivy.

Poison Oak Leaf Clusters

One of the distinguishable characteristics often used to identify poison oak is that like poison ivy, the leaves grow in clusters of three. However, this isn't a hard and fast rule since poison oak leaves can also appear in clusters of five or even seven.

  • Poison oak leaves are similar to actual oak leaves and can be difficult to distinguish between the two.
  • Poison oak produces white berries.
  • In the fall, poison oak joins the various colorful foliage by turning various hues of yellow, orange and red.

Where Poison Oak Grows

You can find poison oak growing as a vine or a shrub. It is predominantly found in western United States, especially in California. However, it can be found in the eastern and southeastern regions of the U.S.

Poison oak vine

Personal Precautions Against Poison Oak

Just as you would with poison ivy, you need to take precautions to avoid skin contact with poison oak. An allergic reaction to poison oak results in a rash that stings and itches. You want to wear long pants. You should also don a long sleeve shirt. You should wear socks and closed shoes. Lastly, you need to wear long garden glove to ensure protection. If using a spray, wear safety glasses and a mask.

Herbicides for Poison Oak

An herbicide is one of the most common ways to kill poison oak. Herbicides such as Roundup® have been blamed for several health concerns. You may prefer Crossbow herbicide designed to kill woody plants. If you opt to use an herbicide, be sure you protect yourself from exposure.

Best Way to Use Herbicide

The best way to use an herbicide is one new growth that is still on the ground. You can spray the leaves to kill the above ground plant. You will need to repeat whenever the plant regrows, but several rounds should eventually kill the plant, having forced it to expend all its energy in re-growing leaves.

How to Use Herbicide on Poison Oak Vines

If you're dealing with more advanced poison oak growth, such as vines climbing up a tree, you need a different plan of attack. You will need to take a few steps before you can spray. Don't spray on windy days since the herbicide could blow back on you. Always spray with the wind, never against it to avoid blowback.


  • Pair of loppers to cut vines
  • Long gardening gloves
  • Clothing to protect skin
  • Garbage bag and tie
  • Safety glasses (optional)
  • Face mask (optional)


  1. Use the loppers to sever the vine at the base. If the vine is too large to cut, you can use a hatchet or axe. The vine on the tree will wither and die.
  2. Spray the herbicide on the exposed stump of the cut vine.
  3. The herbicide will infect the root system and kill it.
  4. Once poison oak root is dead, you can dig it up, careful not to get it on you.
  5. The vine still contains the sap, urushiol, that is very sticky. This is the culprit that causes rashes, so be careful when handling the root.

Kill Poison Oak With Boiling Water

Dousing poison oak with boiling water is one of the oldest and most environmentally conscious ways to kill poison oak. You need to be careful that you don't get the scalding water on other vegetation since it will kill whatever plant life it touches. Boiling water isn't a permanent solution, since you'll need to repeat it whenever replacement leaves grow.

Boiling Water

Non-Poisonous Sprays You Can Make

You can make a spray that will kill poison oak that isn't as harmful as an herbicide. You can make a spray using vinegar, salt and a few drops of liquid dish soap.

Supplies for Vinegar and Salt Recipe

You will use this spray on the poison oak leaves.

  • 1 garden sprayer
  • 1 gallon distilled white vinegar
  • 3 cups of table salt
  • 4 teaspoons of non-detergent liquid dish soap

Instructions for Vinegar and Salt Recipe

This will kill the leaves, but not the plant, so you'll need to repeat the process each time new leaves emerge. Eventually, after enough uses, the poison oak plant will exhaust itself and die from expended energy reserves. Mix the vinegar, liquid soap and salt in the sprayer well.

  1. Sir or shake the solution to thoroughly mix.
  2. Spray mixture onto poison ivy leaves.
  3. Repeat when new growth emerges.

Vinegar and Dish Soap Mixture

You can simply use a gallon of distilled white vinegar and tablespoon of liquid dish soap for an effective treatment. The soap aids the vinegar in sticking to the leaves.

Vinegar and Dish Soap Mixture

Salt, Water and Dish Soap Spray

If you don't have a gallon of vinegar or simply prefer a non-vinegar spray, then you can mix 5-6 cups of salt, 1 tablespoon of non-detergent liquid dish soap with a gallon of water. Allow the salt to dissolve before spraying. Be careful to avoid other vegetation.

Cut Vine and Use Mixture

You can also tackle the vine the same way described for using an herbicide. Instead of spraying the stump, douse the vine stump with on of the homemade solutions, allowing it to seep into the ground and saturate the roots below.

Animals That Eat Poison Oak

Most animals don't have allergic reactions to poison oak. If you have livestock, such as cows, sheep or goats, allow these animals to feast on the poison oak leaves. Goats are especially good at clearing poison oak from the ground and in many cases tree trunks.

Goat Eating Leaves

Let Animals Graze Early Spring

Most farmers and ranchers don't let their livestock graze until the pasture grasses are about 6' to 10" high. You can allow your livestock, especially goats to munch on the new growth of poison oak to keep it from growing rampant. You'll need to periodically allow your livestock to graze on the poison oak when it grows another set of leaves. It may require up to four or more times until the plant dies from over-production of leaves, having depleted it of its store energy.

Ways How You Can Kill Poison Oak

You can explore the different ways to kill poison oak. Each has its pros and cons, but you should be able to select one that will work for you.

How to Kill Poison Oak