Winning the War on Mile-a-Minute and Kudzu
Nevin Dawson, Forest Stewardship Educator, University of Maryland Extension
Barry Rice - Sarracenia.com, Bugwood.org
Mile-a-Minute Weed; Persicaria perfoliata;
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
You lounge in the sun on your patio, surrounded by a mix of forest and meadow. Your favorite magazine drops from your fingers as you nod off in the pleasant afternoon warmth. Slowly waking from your nap an hour later, you move to stretch your arms. But something is wrong—you can’t move. Startled and now fully awake, you look down and see that leafy vines grew over you while you slept, loosely binding you to your chair. You quickly wrench yourself free and march to the shed for the machete.
Mile-a-minute and kudzu are both exotic invasive vines from Asia that grow extremely quickly. Although neither could actually engulf anyone in an hour, mile-a-minute and kudzu can grow 6 and 12 inches per day, respectively, under optimal conditions. This fast growth and their climbing nature allow these vines to cover trees, houses, and vehicles when left unchecked. In a natural area, they can crowd out most or all native species.
Both of these species have a growing foothold in Maryland, but the viney wastelands they can create are luckily not yet common in our state. Both vines grow best in full sun and often get started in disturbed areas and forest or road edges—all common conditions in Maryland. It is up to the vigilance and quick action of you, the landowner, to keep these virulent pests at bay.
Kudzu was intentionally introduced and promoted in the United States as an ornamental, forage crop, and erosion control measure. It has spread quickly enough in southern states to earn the label, “the vine that ate the South.”
It’s a perennial semi-woody vine with alternate, deciduous, compound leaves with three broad leaflets, each up to 4 inches across. Leaflets are hairy and may have lobed edges. Its purple flowers are a half inch long, and grow on upright stalks in the late summer. Flat dry hairy bean pods develop from the flowers.
The plant is probably not spread much by seed, but by rooting of stem nodes. This means that simply dropping a stem in a new site can be enough to start a new infestation. The huge tap root can weigh up to 400 pounds and support as many as 30 vines, each up to 100 feet long.
Kudzu has many uses. The vines can be woven into baskets, the roots can be eaten and are said to cure alcoholism, and the plant could produce as much bioethanol per acre as corn. These benefits can be used as an incentive for control, but kudzu should never be planted.
Mile-a-minute is an herbaceous annual vine that was accidentally introduced in Pennsylvania. It favors wet areas and stream banks, and can easily spread downstream by dropping its buoyant seeds into the water. Its triangular leaf and sharp backward-curved barbs give it its other common name—Devil’s-tail tearthumb. It also has unique circular leaves that surround the stem at each node. Small white flowers and clusters of berry-like blue fruit emerge from these circular leaves. Birds spread the seeds long distances.
Both vines can be controlled with a foliar herbicide treatment with glyphosate—like Accord® or Roundup®—or triclopyr—like Garlon® 4 or Element® 4. Kudzu requires a 2% mix, while mile-a-minute only needs 1%. Spray after mid-July so the herbicide is transported into the roots and kills them. Mechanical control with mowing, hand-pulling, or grubbing is also effective. Targeted grazing with goats or sheep also works, especially in locations where access is a problem, or where herbicide use is not preferred.
It’s important to understand that when fighting kudzu, you’re battling the large energy reserves in its taproot. If you’re using mechanical control, you’ll need to cut the vines several times over the course of a few years before the plant runs out of energy to resprout.
In battling mile-a-minute, on the other hand, you’re fighting the seed bank. Make sure to cut or spray the vines before they go to seed, and continue to control the new vines as they germinate. Small vines can be easily pulled by hand. Seeds are viable in the soil for up to 6 years, so persistence is required. Sites with a heavy infestation may benefit from treatment with a pre-emergent herbicide.
Promising biological controls are under development for both species. A naturally-occurring fungus shows great promise for the control of kudzu. A weevil that attacks mile-a-minute is being studied through a release and monitoring program, and should be available for sale to the public from the New Jersey Department of Agriculture in 2012.
This article was previously printed in the Fall 2011 issue of Home and Garden News, the Delmarva Farmer and UME’s Branching Out newsletter. Branching Out is published four times per year and distributed to forest landowners, resource professionals, and others interested in forest stewardship. Visit the Forest Stweardship Education web page for subscription information.
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