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Air potatoes

July 21, 2017
By JOYCE COMINGORE - Garden Club of Cape Coral , Cape Coral Daily Breeze

By JOYCE COMINGORE

news@breezenewspapers.com

They're coming - the invasion of the territory snatchers.

Years ago, a gardening friend asked me if I wanted a beautiful vine with heart shaped leaves. Always the gardening adventurer, I said yes. I really did plant it. Trying to train it up the open concrete wall at the very front of my home, it didn't seem to like the hot concrete.

The leaves were beautiful indeed and I looked forward to the bloom which I was sure would be beautiful. They are dioecious with both male and female flowers on separate plants, but it is uncommon for them to flower in Florida.

Nubby, pimply gray potatoes showed up, that reproduced the instant they touched the ground, which is one of their ways of reproducing. They didn't really climb, but spread everywhere. It was then I found I had planted the nearly number one invasive noxious weed plant, listed since 1993.

Dioscorea bulbifera is in the yam family, native to Asia and the sub-Saharan Africa. Introduced to Florida in 1905, it soon began to displace our native species, and disrupted our fire and water flow.

Spreading underground as well as producing their arial tubers or bulbils on vines above ground, which can measure 6 inches in diameter, a bit like a lumpy softball, they are in a rush to take over the territory.

Bulbils can take a year or more to sprout. Soil contact is not necessary for sprouting,

Capable of twining 70 feet or more with alternately arranged heart-shaped leaves, air potatoes can grow to at least 8 inches long and nearly as wide, whose veins are raised higher than the leaf. Growing roughly 8 inches a day, it climbs to the tops of whatever they latch onto and take over. Even though they die back in the winter, the easiest time to find and destroy them, they are busy underground spreading, sprouting again in the spring. Particularly spreadable along waterways where water can float them and disperse them extensively, they need to be carefully watched. They do dislike saltwater.

Combating them took a good deal of my time. Constantly monitoring them, picking them up into disposable bags, I had to dig for some roots as I didn't dare leave any trace of the vine. It took me a good year and a half to satisfactorily complete that job.

I hate to use chemicals, but Round-up sprayed on the leaves would have carried the potential killing to the roots, but I was determined to be chemical free.

Charlotte County has available for its constituents only, a program distributing Air Potato Beetles that chew the vines to death. The beetles, selective eaters, only eat air potato leaves. One must fill out a record sheet for the further studies of infestation sites offered by Min B Rayamajhi, Ph.D., with the Invasive Plant Research Laboratory in Fort Lauderdale. The leaf feeding beetle from Asia, Lilioceris chenI, was released in Florida as a biological control agent in late 2011. It has been released here in Lee County for several years now, so, it should be established here. The beetle was discovered in Nepal by the Fort Lauderdale scientists who went there to study the air potato.

Adult beetles are either bright red or brown, about 3/8 inches long, and live for up to six months. They lay as many as 4,000 eggs in clusters under the fresh new leaves of the vine. The adult female bites the leaves veins where they ovipost, causing the leaf to curl up over the laid eggs, protecting them from the elements and predators. The eggs hatch in about 4 days. The reddish larvae feed on the leaves for 10 days. Occasionally, the late stages of larvae and adults will feed on the bulbils. When mature, the adults drop to the ground, burrowing into the soil, make their cocoons, emerging after 16 days, and lay their eggs 15 days later. The caterpillars often feed in groups on the growing tips, inhibiting the vine's growth and stopping the vine's ability to grow.

As winter time hits and vines wilt, the adult beetles drop to the ground, enter a resting state beneath the leaf litter or debris on the ground, emerging in the spring with the sprouts of the bulbuls, feeding and laying eggs. The process repeats itself. Since they only feed on the Florida air potato, their release was allowed and a permit to be issued for their release in 2011.

No such program is being offered by Lee County, but you can send to Min B Rayamajhi at USDA/ARS Invasive Plant Research Laboratory, 3225 College Ave., Fort Lauderdale, FL, 33314, for beetles along with a survey to fill out. This will help with the studies and future remediation.

Some of Florida's counties have a physical round-up, recruiting volunteers to help, protect and conserve Florida's natural areas by this removal.

Climbing vines should be pulled down to minimize damaging desirable vegetation. Try not to disconnect the vines from the ground bulbils, so you know where to dig or spray chemical control that needs to reach into the bulbils. The best time to spray is in the spring and summer.

If you can't burn them after gathering, you can freeze them overnight to kill them.

Cold intolerance is what limits their spread to larger areas beyond the tropical/sub-tropical climates. It is a Category I invasive exotic plant in Florida.

In many parts of the world it is used as food and cultivated as an agriculture crop; also used as a folk medicine. I prefer to listen to those who say - "Do not eat."

When you see any tree, thank it.

Joyce Comingore is a Master Gardener, hibiscus enthusiast and member of the Garden Club of Cape Coral.

 
 
 

 

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