UF Researcher: Cutting-Edge Device Could Thwart Weed Invasion

February 25, 1998

IMMOKALEE — “Cutting-edge technology” could help defeat an aggressive weed that has spread through South Florida and is marching north, University of Florida researchers say.

“The technology literally is a cutting edge — a new device that dispenses weed killer along the blade of a mower,” said Jeff Mullahey, associate professor of range management at UF’s Institute of Food and Agricultural Sciences.

When Mullahey learned of the technology, he decided to test it at an Immokalee area ranch. His tests showed that it works well against the tropical soda apple weed, a nasty relative of tomatoes and peppers.

Since arriving in Florida from South America in the early 1980s, the soda apple has edged out grasses and native vegetation in thousands of acres of pastures, roadsides and nature preserves. “This is our best hope in beating it back,” Mullahey said.

Although he focused on the soda apple, he believes the invention will work well against other unwanted plants, including seedlings of another exotic menace, the melaleuca tree. “We’re still learning which herbicides work best with it,” he said.

The apparatus drips weed killer onto the blade of a farm mower, and centrifugal force spreads the chemical along the blade. “The neat thing is that the weeds suck in the herbicide through the mown leaf edges and stems,” Mullahey said.

He calls the device “stealth technology” because it leaves no visible trace of weed killer and the herbicide is applied directly to the weeds. “When we started using it, I wasn’t sure any herbicide was going onto the weeds,” he said. “We had to use a blue dye to be sure it was working.”

The new approach is good for the environment because none of the herbicide spreads to nearby plants, animals or people. Weed spray sometimes turns into a gas that is carried by the wind and has killed plants up to 20 miles from where it was applied, Mullahey said.

The device also cuts out the expense of spraying for weeds after mowing. “Besides, mowing alone will not control soda apple,” Mullahey said. “It comes back like gangbusters.

“More and more farmers, ranchers and road superintendents are considering the device,” he said. “Once the word spreads that it’s so much better than spraying, it could become the standard for weed control.”

The new technology may be vital to Florida’s cattle industry. Calves and adult cattle carry soda apple seeds in their bellies. “When animals are shipped to other states, the seeds spread through their manure,” Mullahey said. “Our cattle industry could be threatened if we don’t get the soda apple under control.”

One of Florida’s largest ranching companies, Lykes Bros. Inc., is enthusiastic about tests it conducted in cooperation with Mullahey. “It’s not economical to spray all of our pastures each year, but this equipment should let us treat for soda apple in all of them,” said Eric Anderson, a Lykes Bros. pasture supervisor based in Palm Dale.

The equipment could save the company thousands of dollars by eliminating the $3.50-per-acre cost of spraying, he said. “It’s not as damaging to our pasture grass, and we won’t have to watch the weather for the right conditions for spraying,” Anderson said.

Other UF researchers are focusing on ways to restore native plants in wild land after weeds are killed off.

“We don’t just want bare ground,” agronomy Professor Donn Shilling said. “This device can kill weeds without destroying desirable vegetation close to the ground.”