Weed control issues are the hot topic this summer. The majority of questions posed to the Extension Office have related to identification and eradication of weeds in the lawn and weeds in landscape plants. The latter is the focus of this discussion. The weeds that have been showing up in ornamental plants have been vines.
There are three main weedy vines in our area that will consume the landscape if left unchecked. They are greenbriar, Virginia creeper, and poison ivy. All of these can be controlled when treated properly.
Greenbriar can be a tough weed to get rid of in your beds. It is often found growing in and among other plants, and usually will appear in the middle of a shrub.
It also will wrap itself around the branches of the plant as it grows. Greenbriar is the common name for plants of the genus Smilax, which contains around 15 species. Its leaves are heart-shaped and appear waxy. Female plants bear seeds with a hard coat that can remain viable for several years.
When greenbriar shows up in the landscape it seems to “pop-up” over night. Greenbriar is able to survive low light conditions and can easily survive in the deep shade under the canopy of a shrub. It usually takes two or three years to “pop-up” from plants canopy that it has been hiding in. During this time it will have developed an extensive underground rhizome/tuber system.
This tuberous system makes greenbriar somewhat difficult to control. The tuber stores carbohydrates for regrowth; so simply cutting the top off of the plant won’t control it.
The best control for greenbriar is to dig up the tuber and dispose of it.
Virginia creeper and poison ivy are often confused with one another. Virginia creeper has leaflets of five, while poison ivy has leaflets of three. Both are vigorous growers and can quickly consume landscape plants.
There are two control options for poison ivy and Virginia creeper growing amongst landscape plants. First, unravel the vines from around the tree or shrub.
Use protective wear when handling poison ivy or both if you can’t correctly identify the plant you’re trying to remove. Glyphosate needs to be applied directly to poison ivy foliage.
The best control is achieved when glyphosate is applied on a warm, sunny day when plants are actively growing. Glyphosate requires a one-hour rain-free period for maximum activity. Glyphosate is a systemic herbicide and is translocated throughout plant leaves, stems and roots. Lay the vine on bare ground or a piece of plastic and spray a 5-percent solution of glyphosate.
A second option is to cut the vine as close to the ground as possible. Immediately paint the cut stem (leading to the roots) with concentrated 41-percent glyphosate. Make this application with a foam paintbrush.
Simply soak the foam brush in the glyphosate herbicide and dab it on the cut stump.
Unfortunately, there are no selective herbicides available today that can be used on these vines without harming the plants they are growing on.
If the vines are growing away from other landscape plants, use products containing 2, 4-D and dicamba, glyphosate, or triclopyr for best control. These products can also be combined for better results but always read and follow the labeled instructions for these applications.
Remember to shield ornamental plants when using these products.
If these herbicides come in contact with the desired plant material it could be harmed or killed.