Common Name: Chinese Yam, Cinnamon vine, Air potato
Scientific Name: Dioscorea oppositifolia L.
Chinese yam is a deciduous perennial vine native to China. It is a member of the Dioscoreaceae or Yam family. The genus Dioscorea has economic value as a food plant and is used as a traditional Chinese medicine.
Origin and Distribution
Chinese yam is native to China. It was introduced to the United States as an ornamental or edible food crop in the 1800’s. Since that time, it has been identified in most of the Eastern United States from Texas to Florida and Vermont to Kansas.
The native wild yam (Dioscorea villosa) may resemble Chinese yam. Main distinguishing characteristics of wild yam include vines that twine right to left, pubescence present on the upper leaf surfaces, and the absence of aerial tubers. Greenbrier (Smilax sp.) has a similar leaf shape to Chinese yam but lacks the bulbils, has thorns (on some but not all species), and has blue to purple berries. Morning glory (Ipomoea sp.) and bindweed (Convolvulus arvensis) have a cordate leaf shape but lack the aerial tubers.
Chinese yam is found in rich alluvial soils along streams, seasonal creeks and rivers. It can tolerate semi-xeric sites with rocky soils. It grows in full sun and can tolerate all but the deepest shade. D. oppositifolia can be found along roadways, waste places, old home sites, and disturbed areas.
Mowing/Cutting: This method is appropriate for small initial populations or environmentally sensitive areas where herbicides cannot be used. Mowing or cutting will control the spread of Chinese yam, but will not eradicate it unless it is continued for several growing seasons or until the root reserves are exhausted. Stems should be cut at least once per growing season as close to ground level as possible. Treatment should be completed prior to bulbil production typically in July.
Grubbing: This method is appropriate for small initial populations or environmentally sensitive areas where herbicides cannot be used. Using a pulaski or similar digging tool, remove the entire plant, including all roots and bulbils (if present). Juvenile plants can be hand pulled depending on soil conditions and root development. Any portions of the root system not removed will potentially resprout.
Mulching: Mulching is an effective control on small infestations or in areas where herbicides cannot be used. Cover the entire infestation with several inches of mulch. This may include wood chips, grass clippings, hay or similar degradable plant material. Shredded or chipped wood may be the best option since hay and grass may potentially carry weed seeds. Covering the area with cardboard may improve the effectiveness and longevity of this method. The mulch should stay in place for at least two growing season and may need to be augmented several times.
Foliar Spray Method: Use this method to control large populations. The most effective time to treat plants is after the leaves are fully expanded but before the aerial tubers are ripe.
Glyphosate: Apply a 4% solution of glyphosate and water plus 0.5%-1% non-ionic surfactant to thoroughly wet all foliage. Do not apply so heavily that herbicide will drip off leaves. Glyphosate is a non-selective systemic herbicide that may kill non-target partially sprayed plants. Ambient air temperature should be above 65°F.
Triclopyr: If native grasses are intermingled with the Chinese yam, triclopyr is preferred since it is selective to broadleaved plants. Apply a 4% solution of triclopyr and water to thoroughly wet all foliage. Do not apply so heavily that herbicide will drip off leaves. A 0.5%-1% non-ionic surfactant is recommended in order to penetrate the leaf cuticle, and ambient air temperature should be above 65°F.
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