Feb. 11, 2010 - Though it may sound pleasant, Tropical Soda Apple (TSA) can actually be a menace to society, especially landowners and agriculture producers.
Tropical Soda Apple, which is native to Argentina and Central Brazil, was first found in this country in Florida. The original infestation increased from a couple thousand acres to more than a million in six years. The first positive identification in Texas came in the summer of 2004, in Jasper County. The landowner who first found it on his property said he suspected he brought it in with a load of Louisiana hay in 1998.
"Tropical Soda Apple was a gift from South America to Florida, sort of like the fire ant," Texas AgriLife Extension forage specialist Larry Redmon said. "They didn't ask for it, but they got it anyway. About five years ago, it showed up in East Texas. Recently, we've seen it in the Brazos Valley."
While TSA has been a major problem in Florida, Texas has been able to battle the plant more successfully than Florida, according to Mary Ketchersid, an AgriLife Extension pesticide safety specialist. Florida has been limited in how it can treat the plant because of a significantly lower water table than Texas, she said.
"Mostly, we treat it like any perennial broadleaf," she said. "It has a strong root system and you have to treat it more than once."
The innocent-sounding shrub, which can grow from three to six feet tall, is an upright perennial with leaves that look like oak leaves. It produces tiny white flowers and green to yellow fruit, about the size of a golf ball. Livestock and wild animals don't like the spiny foliage, but they love the fruit. Each fruit contains about 100 seeds and the animals that eat the fruit spread the non-digestible seeds far and wide.
Tropical Soda Apple is often confused with Carolina or Western horse nettle, which don't grow as high as TSA. The horse nettle flower is larger and generally purple with bright yellow anthers.
"The real key for identifying it is to look at the flowers," Ketchersid said. "If it has big bright yellow anthers, it's horse nettle. TSA has a smaller white flower and the anthers are pale, maybe tan, but never bright yellow."
A Texas AgriLife Extension booklet on TSA written by Ketchersid, Redmond and AgriLife Extension weed specialist Paul Baumann recommends broadcast applications of Grazon P+D (1 to 2 quarts per acre), Remedy (1 to 2 pints per acre), Surmount (3 pints per acre), and Tordon 22K. Individual plants can be treated with Roundup Ultra (2 percent solution), Remedy (1/2 to 1 percent sulution), and Grazon P+D (1 percent solution.) Both broadcast and individual treatments should include a good agricultural surfactant to help herbicide penetrate the plant.
For dense infestations, mowing the plants to a three-inch stubble to keep the plants from producing fruit and seeds is recommended. Mowing should be repeated 50 to 60 days later when the plant is in the first flower stage. Herbicides should be applied at the first flower stage, usually in late May or early June.
"Remember that broadleaf applications can hurt any broadleaf plant," Ketchersid said. "Be especially careful not to spray under or around trees."
Ketchersid, Baumann and Redmon got involved with the initial outbreak in 2004. The first batch of Texas TSA had been growing for a few years before the landowner realized he had a serious problem on his hands and reported it to the Jasper County Extension agent. The Extension personnel, along with a pest survey team from the USDA and a Texas Department of Agriculture entomologist visited the farm soon after.
Since then, the plant has popped up at various places, but has not "taken over" like it did in Florida and other places. For one thing, Ketchersid said, the plant doesn't like hot and dry weather, and much of Texas has had just that kind of weather for the last two years, up until this winter.
Another outbreak occurred when a landowner probably brought the seeds in with out-of-state cattle that hadn't had a two-week "cleanout." The landowner jumped on the problem quickly and was able to control it before it got out of hand.
"We haven't had the problem with it that Florida has had, but it can become a problem quickly once it gets established," Ketchersid said. "Getting to it early and providing more than one treatment is the key to controlling it."
