Poison oak, which causes contact dermatitis in many people, can be found anywhere that has at least 8 inches (20 cm) of rain a year. Getting rid of this plant can be difficult, because it is hardy and quick-growing. While the most effective method of removal is manually pulling the plant from the ground, smothering it or applying herbicides to the stems and leaves can also be effective ways of killing poison oak.
Manually removing poison oak should be done in the spring or fall, when the ground is soft and the roots can be easily pulled from the ground. To avoid coming in contact with the plant's urushiol oil, which causes the rash associated with poison oak, long sleeves and at least two layers of gloves should be worn. It is also possible to kill poison oak by smothering the plant. This involves cutting the vine or shrub down to between 1 inch and 2 inches (2 cm to 5 cm) above the ground and covering the remainder of the plant thoroughly with heavy tarp, newspapers or anything else that prevents it from growing. While smothering is not the best way to kill large quantities of poison oak, it works well when there are only one to two plants.
Herbicides such as glyphosate and triclopyr can also be used to kill poison oak. It is best to apply them when no rain is expected for at least two days; this gives the toxin time to soak into the plant. As with smothering, the plant needs to be cut down to between 1 inch and 2 inches (2 cm to 5 cm) above the ground. The toxin should be applied to the freshly cut stems immediately after cutting the plant. This ensures that the poison makes its way throughout the plant and into the roots.
Herbicides can also be sprayed or brushed onto the leaves or vines of the poison oak plant. This application is best done while the plant is flowering. When spraying, it is important to make sure that there is little to no wind, because the wind could prevent the herbicide from reaching its intended target, reducing the effectiveness of the herbicide and possibly harming other plants. If the poison oak is growing as a vine on a tree, it is best to brush the toxin onto the leaves to reduce any possible damage to the tree from errant spray.
Those who plan to kill poison oak, whether manually or through the use of herbicides, should make sure they are not overly sensitive to the plant and, if possible, hire someone who is not allergic to it at all to handle the killing and removal. It is also important to properly dispose of all parts of the dead plant, because poison oak can still cause contact dermatitis for up to five years after it dies. Other than wearing the proper attire and removing or spraying plants at the right time of year, it is also important to never burn poison oak plants, because the smoke can cause severe reactions when the toxin is released into the air and inhaled.