Q: I have some poison ivy in my backyard, and I am very allergic, so I’d rather not touch it. Are there herbicides that will kill it, and when is the best time to apply them?
A: Poison ivy can be difficult to kill, particularly if it is mature. If you are unable to find a professional who can tackle the poison ivy for you, management strategies vary depending on the size and maturity of the plants.
If you feel comfortable, seedlings can be easily pulled when they are small while wearing disposable nitrile or latex gloves. For larger plants or vines, herbicides made to kill poison ivy and other vines or brush that contain the active ingredient triclopyr or glyphosate tend to be most effective. Both of these active ingredients get taken up by plants via leaves, bark or cut stems and are therefore able to harm all parts of the plant including the roots.
For best control, apply herbicide between late spring and early fall while poison ivy is actively growing. Note that mature plants may require multiple applications to kill them completely. It is important to read and follow all instructions on product labels before applying to ensure both safe and effective use of pesticides. Pay attention to whether the product will harm ornamental plants that may be growing nearby, as you might need to protect them from being sprayed while treating the poison ivy.
If the poison ivy is larger and has thick stems, cut them near the base and immediately apply herbicide to the cut stem. If the plants are small but you don’t want to pull them, their leaves can be sprayed with herbicide. Keep an eye out for regrowth, which can be sprayed provided the product instructions allow for repeated applications.
Write to the Missouri Botanical Garden’s Center for Home Gardening at plantinformation@mobot.org or the Horticulture Answer Service, 4344 Shaw Blvd., 51ºÚÁÏ, MO 63110.
