Stemming the invasive air potato


Published: Saturday, January 31, 2004 at 6:01 a.m.
Last Modified: Friday, January 30, 2004 at 10:50 p.m.

Each and every one of us are stewards of the environment. You may not realize it, but it's true. Everything you do in your yard has consequence elsewhere.

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The tubers (bulbils) of air potato vine are formed at the axils of the leaves on the long vines. Each is capable of sprouting, whether it's in contact with soil or not.

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This is particularly important in subdivisions or neighborhoods where houses are close together. You may think of it as your yard, but it is really just a small piece of the large quilt making up the urban or suburban landscape.

I came to this conclusion several years ago as I saw my little pond get covered with duck weed. When I moved in, it was clean and clear, with resident soft-shelled turtles, plenty of small panfish and a sizeable bass we named Fred, who was caught and released a half a dozen times.

Turtles proliferated, and there was a 3-foot alligator who sunned on the other bank and occasionally floated around atop a piece of plywood. Plenty of herons staked out their territories along the bank, and wood ducks returned every winter and raised a small family.

But then several neighbors took their lawns a little too seriously, and began a regimen of weed-and-feed and fertilization. Their yards looked nice, but they were a little too exuberant in their application rates.

My pond is the retention basin for our end of the neighborhood, and runoff enters via storm sewers.

It began slowly, but over the years, the surface became completely covered. The turtle population fell; there is only one Great Blue and one Green heron stalking the banks; and the wood ducks come to visit, but they no longer nest nearby.

Chinese tallow trees began to appear in the runoff areas, most noticeable in the fall when their foliage turns ruddy. And out of nowhere the air potato vines started their slow-but-sure stranglehold.

Now, I freely admit to once deliberately growing air potato vines - but it was back in the days when "exotic invasive" wasn't a common phrase. The quilted, heart-shaped leaves and exuberant growth were handy when I needed a quick cover-up for a fence.

Little did I know I was dealing with an explosion about to happen. When cleaning up the yard, I would casually throw the "potatoes" into a vacant lot next door. Forgive me; I knew not what I was doing.

I now prowl my yard for the first sign of Dioscorea bulbifera, the fancy name for air potato vine, which is our equivalent of kudzu (which does appear in some Gainesville sites, but so far hasn't made as strong an impact).

Air potato vine is native to Asia and Africa and has been widely naturalized in all tropical and subtropical parts of the world. It appears in nearly every part of Florida, and while I haven't seen it myself, I suspect it is in southern Georgia and Alabama as well.

According to "Identification and Biology of Non-Native Plants in Florida's Natural Areas" by Ken Langeland and K. Craddock Burk, air potato vines came to this country from Africa during the slave trade and were introduced to Florida in 1905 by the USDA for agricultural purposes.

Henry Nehrling, an Orange County horticulturist, received a sample from the USDA at his research station in Gotha in the mid-1940s and wrote that he "had never seen a more aggressive and dangerous vine in Florida."

I suppose I've read understatements before, but that one is a classic.

One single tuber (they're really bulbils) left to its own devices has the capability of eventually covering acres of land, its tall (more than 60 feet long) twining vines covering native and desirable vegetation, choking and shading everything in their path.

At most leaf axils, tubers grow, each of which will sprout the following spring - if in contact with the soil or not. An example of this: I had collected perhaps a five-gallon bucket of tubers from my yard one fall. I didn't want to place them in the yard waste (where they would eventually be "planted" where yard waste is trucked to) so I had planned on incinerating them in the quite-hot bonfire we routinely burned in the back.

But I forgot about the bucket, which was placed under the workbench in the garage. One day the following spring I found the most eerie sight: every single tuber had sprouted in that bucket, and had created a massive rope that wound its leafless way to the single window.

There are several ways to control and try to eradicate this pest, and all involve aggressive action.

If you cut the vines down early in spring, as they emerge, you will eventually weaken the underground tuber to the point it won't sprout again. If you only have a few vines, dig up the tuber itself. Scout around the area for the smaller ones lying around.

While they can grow to almost fist size, even the bulbils that are the size of your thumbnail are capable of sending up a full-length vine. Killing the vine before midsummer, when bulbil production begins, will eliminate a new crop.

Air potato tubers are among the very few vegetative items you are allowed to place in your garbage container. Do not leave the vines for yard waste collection, as this would only serve to propagate them in another place.

If you want to help eliminate this pest in public parts and nature areas, join in today's Great Air Potato Roundup from 8 a.m. to 1 p.m. Collected tubers will be brought to Morningside Nature Center for disposal. There will be food, music, prizes and contests for the largest and funniest tuber collected.

Each year more than 5 tons of tubers are collected, and while this is significant, it hasn't made a lasting impact on the natural areas. It's up to all of us to continue the fight.

Marina Blomberg can be reached at 374-5025, or gardener@gvillesun.com.

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