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'Weed from hell' found in Texas

JASPER – An infestation of tropical soda apple, a thorny plant on the federal noxious weed list, has been verified on a private ranch here.

Called alternately the "plant from hell" and "Sodom's apples" in Florida, the thorny weed can quickly take over pastures, first displacing the grass, then the cattle, said Dr. Mary Ketchersid, Texas Cooperative Extension pesticide safety specialist.

Ketchersid said she doesn't want to sound like an alarmist, but the weed has caused economic disaster for agricultural producers in other states.

"I think we need to be scared. People need to be watching for it," she said.

Dr. Larry Redmon, Extension forage specialist based in East Texas, agrees.

"I think people need to be very concerned because it has the potential to cover a lot of acres in East Texas in a short period of time," he said.

A rapid response team comprised of Extension range management, weed and forage specialists, U.S. Department of Agriculture pest survey personnel and a Texas Department of Agriculture entomologist, visited the Jasper farm soon after being alerted by Ricky Thompson, Extension agent for Jasper County.

The hope is, Ketchersid said, to contain the weed to the original site. But she warns that since it's a perennial, eradicating it isn't likely to be easy.

"We've been trying to eradicate mesquite since before the 1960s, and it's still the subject of brush control programs," she said.

Before they spray a suspect infestation, producers should first send a sample to Ketchersid for positive identification. Take a generous sample and seal it up in a gallon plastic storage bag. Be sure to include leaves, stems and fruit. Don't add any water. Using a sturdy cardboard box, mail the bag to Mary Ketchersid, 115 Agronomy Field Lab, 2488-TAMU, College Station, Texas 77843-2488.

Alternately, producers may also call Ketchersid at 979-845-6531, or e-mail digital photos of the suspect plant to her at [email protected]

It's important that landowners act promptly if they suspect they have the weed for it can spread rapidly, Ketchersid said.

"The landowner told us in a meeting that he had probably brought it in with a load of Louisiana hay in 1998. He's been trying to control it himself for years, and now it's a real mess," she said.

Many treatments are likely to look good at first, killing most of the weed's foliage. But with perennials, if the herbicide isn't carried to the roots, the plant may soon recover by the next growing season.

"The control can look really good right now, but in the next year, if the roots haven't died, the plant can come back," Ketchersid said.

The perennial weed produces small fruit about inch in diameter, dark green with light green stripes. Resembling small striped watermelons, the fruit or "apples" contain more than 100 seeds and are readily eaten by cattle and wildlife, including deer, wild hogs, raccoons and birds. The seeds, which are not digested, may be quickly distributed over a wide area, Redmon said.

The weed is native to Argentina and central Brazil. In the United States, it was first found in Florida. Infested areas there increased from a couple of thousand acres to more than a million in six years, Redmon said. The weed has taken over hundreds of thousands of acres in Florida, Alabama, Arkansas, Georgia and Louisiana.

"Because TSA produces an unpalatable foliage that goes ungrazed by livestock, the plant can rapidly spread over pastures and in woodlands, thus reducing stocking rate and negatively affecting livestock production systems," Redmon said.

When mature, tropical soda apple can reach 6 feet in height and have a stem 1 inch in diameter.

Stems, leaves and flower stalks have white to yellowish spines up to an inch long. Young leaves are 4 to 7 inches long and 2 to 6 inches wide, deeply divided into broad pointed lobes and usually about as long as they are wide.

Flowers are white with yellow stamens and are located beneath the leaf canopies.

"Tropical soda apple may be confused with Carolina horsenettle; however, horsenettle usually does not grow as tall as TSA," Redmon said.

Also, he noted, the flower of the Carolina horsenettle is usually purple, not white.

"But you do occasionally see a white flower on horsenettle," Ketchersid said.

Control recommendations in other states are to mow the infestation as early as possible to a 3-inch stubble. Wait 60 days until it's in the flowering stage, then mow again. When plant growth is in the first flower stage actively growing, spray with a broadleaf herbicide such as Remedy. Use one quart per acre with labeled rates of nonionic surfactant in 40 gallons/acre of water, Redmon said.

By the time the task force learned about the Jasper infestation, it was too late in the season to follow these recommendations, said Dr. Paul Baumann, Extension weed control specialist and another member of the task force.

Baumann took the opportunity to try 13 treatments including nine over-the-top broadcast and various spot treatments to see what looked most effective.

"We know what works in other states, but we don't know for certain what works here on our soils and environment," he said. "We want to find the most economical solution, one that uses the least amount of herbicide (for effective control.)"

The testing went well, Baumann said.

"Preliminary results two weeks after treatment indicated several products showed promise," Baumann said.

These treatments included:

1 pint/ acre of Tordon 22K gave 60 percent to 70 percent control. 3 pints/acre of Surmount, a new product, gave 75 percent to 80 percent control. In both cases, plants were 12 to 36 inches tall, and Baumann used a 0.5 percent non-ionic surfactant, he said. "This was only after two weeks. I expect some improvement in control as these products have longer to work," Baumann said. In spot treatments a 2 percent solution of Roundup provided excellent control, Baumann said. (In spot treatments, Roundup also has 14-day haying and 14-day grazing restrictions.) Remedy at 1 percent solution provided 75 percent to 90 percent top kill as a spot treatment. "We'd expect to get some root kill from all these products, but we won't know for sure until this fall or next spring," Baumann said. For Web site images and articles from other states, Ketchersid recommended http://www.invasive.org/tsa/ and http://www.ceris.purdue.edu/napis/pests/tsa/. "If it's out there and it spreads, it could be a real economic disaster," Ketchersid said.


Texas A&M University - Agricultural Communications. Public release date: July 7, 2004.

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