AIR POTATO – Dioscorea bulbifera
Air potato was introduced to Florida in 1905 when it was sent to the USDA by Henry Nehrling, who later noted its invasive potential (Morton 1976). It has since become extremely aggressive (Hammer 1998). By the 1980s, air potato vines were growing in thickets, waste areas, and hedges or fencerows in many parts of south and central Florida (Bell and Taylor 1982). By 1999, air potato was recognized as an invasive exotic that alters plant communities by displacing native species, changing community structure, and disrupting ecological functions (FLEPPC 2003).
Air potato is an aggressive, herbaceous vine that can attain lengths of 65 feet in a single growing season. Underground tubers may be present or absent. The slender stems twine to the left (counter-clockwise) and are round to slightly angled in cross section. Leaf arrangement is consistently alternate. The thin textured, glabrous (hairless) leaves, which measure from 2 to 10 inches long, are cordate (heart-shaped) with broadly rounded basal lobes, elongated tips and entire margins. The venation is conspicuous on the upper leaf surface.
In Florida, bulbils are spread by gravity and float on water currents. They are also dispersed by heavy machinery and through movement of contaminated brush and soil; therefore, management of Dioscorea bulbifera is generally labor intensive and expensive.
Eradication:
Intensive control program for air potato includes: 1. A leaf feeding beetle, Lilioceris cheni, was recently introduced into Florida from China for biological control of air potato. Researchers have shown that air potato leaf beetles are host-specific to air potatoes and will not feed on other plants. For more info on the beetle visit: http://entnemdept.ufl.edu/Creatures/BENEFICIAL/BEETLES/air_potato_leaf_beetle.htm 2. Pruning native vines for better access to non-natives; 3. Pruning non-native vines; 4. Hand application of herbicide to non-native vines; 5. Hand pulling non-native seedlings/tubers; and 6. Positioning and pruning native species to facilitate growth and canopy access. It is important to dispose of removed plant material in a secure location to avoid re-germination. Garlon 4, applied at a 10% concentration, provides good control when applied with the basal application method. Completely encircle the lowest 30-61cm of the stem or trunk with the herbicide and form a band at least 15cm wide. Also, slash the roots with a hatchet to inhibit quick regrowth.
Vines form impenetrable thickets that overgrow, break and sometimes topple trees and shade out smaller native understory plants, eventually altering community ecology. (See photo)