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GAINESVILLE, Fla. — A $512,000 grant will help University of Florida faculty test a new triple-threat approach to controlling hydrilla, the state’s most troublesome invasive aquatic weed.
The grant was awarded to UF in September by the U.S. Department of Agriculture, said entomologist Jim Cuda, an associate professor with the Institute of Food and Agricultural Sciences who leads the team of research and extension faculty.
New approaches to hydrilla control are needed, he said, because in some parts of the state the weed has become resistant to the herbicide fluridone, the most popular chemical control agent.
“The resistant hydrilla will probably move out of Florida,” Cuda said. “So this research doesn’t just concern Florida.”
Native to Asia, Europe and Australia, hydrilla was brought to Florida for use in the aquarium trade. It has grown wild in the state since the early 1960s and now infests more than 110,000 acres of lakes, ponds and other surface waters.
The grant funds research and extension activities on a three-part control strategy, Cuda said. It involves an insect that feeds on the weed’s new growth, a fungus that damages the weed, and an herbicide that should make the weed more susceptible to both organisms.
Cuda is studying the insect, an aquatic fly called a midge, to determine the range of water temperatures it can survive. The midge’s larvae eat new hydrilla growth and seem to feed exclusively on that plant, he said. Experiments will show whether the insect attacks native aquatic plants.
A private company that hoped to market the fungus as a stand-alone hydrilla control product found that it damaged the weed but wasn’t cost-effective, Cuda said.
Under the three-part control method, less fungus should be required because the hydrilla will be weakened by the midges, he said.
The herbicide, Imazamox, slows hydrilla plants’ vertical growth and causes them to branch out, creating multiple growing tips for the midge larvae to attack.
Cuda said he hopes the method will prevent hydrilla from forming mats at the water’s surface and instead remain submerged. The plant grows from roots anchored in the bottom.
After researchers confirm the safety and effectiveness of the method, it will be field-tested in local waters, said Jennifer Gillett-Kaufman, an extension specialist based at UF.
One likely site is Jefferson County’s Wacissa River, a spring-fed system that’s choked with hydrilla in many areas, said Raymond Hix, an entomology associate professor with Florida A&M University.
“It’s about as bad as anything you’d see in Florida, especially in a cold water system,” said Hix, a collaborator in the project.
If field tests are successful, the method will be communicated to extension agents around the state, Gillett-Kaufman said. It may be appropriate for use outside Florida as well.
Other collaborators in the study include personnel from a UF research and education center, extension offices and the U.S. Army Corps of Engineers.
Writer: Tom Nordlie, 352-273-3567, firstname.lastname@example.org
Sources: Jim Cuda, 352-273-3921, email@example.com
Jennifer Gillett-Kaufman, 352-273-3950, firstname.lastname@example.org
University of Florida entomologist Jim Cuda, right, and extension specialist Jennifer Gillett-Kaufman remove midge eggs from a glass vessel in Cuda’s laboratory on Monday, Oct. 18, 2010. The two are part of a research and extension team that recently received a $512,000 federal grant to develop a new method for managing hydrilla, Florida’s most troublesome invasive aquatic weed. The method uses an herbicide, a fungus and the midge, an aquatic insect that feeds on hydrilla. Photo by Tyler Jones