By Mark Czarnota
University of Georgia
Weedy vines in the landscape can cause mayhem for even the most proficient gardeners. Among the worst are greenbrier, honeysuckle, Virginia creeper and poison ivy.
Greenbrier (Smilax species) is native to North America. It's related to day lilies, lilies and yucca, but all Smilax species are vines. They all have extensive underground rhizome tuber systems. Most have thorns. The plants can be male or female, and females bear black, blue or red fruits.
Honeysuckle (Lonicera japonica) is a semievergreen vine. Of the 16 to 20 species of Lonicera, only a handful are climbing vines. Most of the vines have woody rhizomes that can be hard to remove. Honeysuckle, has two types of leaves and flowers that produce a wonderful nectar.
Virginia creeper (Parthenocissus quinquefolia) is native and related to grapes and porcelain vine. It grows much like grape vines and can form mass thickets. When not being weedy, Virginia creeper is known for its outstanding fall color.
Poison ivy (Toxicodendron radicans) is a clinging, twining vine. Most people recognize it by the old adage, "Leaves in three, leave it be!" It can produce an extensive, hard-to-remove, underground rhizome system. The plant produces an alcohol-like substance that can cause severe skin reactions, so beware when trying to remove it by hand.
How'd they get into my shrubs?
Many other woody vines can be weedy. But these four all have fleshy fruit that birds relish. When the fruits ripen, birds eat them and can deposit the seeds in the crown of ornamental shrubs.
Seeds that pass through the bird and germinate can get a good foothold before showing up. Once they're visibly growing inside prized shrubs, most gardeners clip out the intruder. Occasionally, this works. More often, though, the vine will keep coming back like an irritating in-law.
Eliminating vines can be difficult
If pruning fails, you can always try to physically remove the plant. This often won't be an option, though, because the vine will have emerged from the center of the shrub. Plants like smilax have an extensive underground rhizome tuber system, too. This makes digging the plant out impossible in such close quarters.
With these options exhausted, you can either try to enjoy your newfound resident or consider using herbicides. Many herbicides are labeled for the control of these vines. Most, however, can't be applied near desirable ornamentals.
One herbicide, glyphosate (sold under the name "Roundup," "Razor" and others), can be used in many ways. Here are two of the best.
- When the plant is fully leafed out (late April to late October), unravel the vine from the desirable plant. If you're doing this with poison ivy, wear gloves and a long-sleeve shirt. Remove as little of the vine as possible, and be careful not to break any stems. Lay the vine on some bare ground or on a piece of plastic. Spray or sponge-apply a 5-percent solution of glyphosate. Make sure the product you use to make the 5-percent spray solution contains 41 percent or greater active-ingredient glyphosate. Be careful not to spray or let the solution drift onto desirable foliage or bark. Allow the vine to sit for 48 hours. Then cut the stem back to the ground. If the treated vine starts to regrow, spray or wipe a 5-percent glyphosate solution to the sprouts when they're 6 to 8 inches tall.
- If the weedy vine can't be unraveled from the desirable shrub, cut it as close to the ground as you can and immediately paint concentrated glyphosate on the cut stem. (Make sure it's 41-percent or more glyphosate.) If the plant regrows, sponge on or spray a 5-percent glyphosate solution when the sprouts are 6 to 8 inches tall.
(Mark Czarnota is an extension horticulturist with the University of Georgia College of Agricultural and Environmental Sciences.)