Armyworms invade the Southeast Monday, September 14, 1998
The mild winter brought on by El Ni¤o has allowed armyworms to invade the Southeast this summer and chew their way through thousands of acres of crops, pasture and turf.
The pests, usually prolific in the summer and fall, got off to a strong start this spring, said Richard Sprenkel, a pest management specialist with the University of Florida's Institute of Food and Agricultural Sciences.
"They showed up very early but weren't much of a problem in April, May and June because the drought stunted vegetation," he said. "The rain that began in July activated fertilizer that had been lying dormant. Greenery exploded, and the worms went to town.
"Early in the summer, we were getting only four to five armyworms in our traps each night," Sprenkel said. "Recently, we've gotten as many as 50 per night."
The outbreak is the worst in 20 years, say experts at universities across the Southeast. They fear that the next wave of the pests will wipe out their fall crops.
Armyworms balloon from a width of two hairs to as fat as a pencil and up to two inches long during their three- to four-week life span.
"When they're full size, they move awfully quick, sometimes destroying a farm field in 48 hours," said David Holmes, Marion County extension service director in Ocala, Fla. "One farmer came in who said it was like his whole pasture was just moving."
Armyworms are eating corn, cotton, peanuts and grasses used for pasture and hay.
"We've had some pastures so decimated that we've had to move cattle just to get them something to eat," said Harrell Phillips, a veterinarian and farmer from Morriston, Fla.
The pests also are a serious threat to lawns, golf courses and athletic fields, stripping almost all the grass leaves, said University of Florida turfgrass specialist Grady Miller. "They wiped out new plantings of grass at two Gainesville playing fields, and I'm getting calls from as far away as Louisiana.
Armyworms have multiple generations so one spraying of a pesticide will not wipe them out.
The pests replace their skins, or molt, six times in their life span. "They do 90 percent of their damage in their last two moltings and go into overdrive the last 48 hours," Sprenkel said.
The pesticide spinosad has proven an effective control of armyworms but it is only licensed for use on cotton, said Sprenkel.
"It doesn't kill most beneficial insects," Sprenkel said. "When you use it, you don't destroy the tiny wasps, spiders and various beetles that are armyworms' natural enemies."
Sprenkel hopes that tests conducted on experimental crops will convince the pesticide manufacturer to go through the necessary paperwork to make licensing it for other crops a reality.
The problem is that doing the paperwork does not make much economic sense, said Sprenkel. "Armyworms tend to be sporadic."
In terms of biocontrols, such as mass releases of the armyworms natural predators, none are effective, said Sprenkel.
"The best method is to stay away from hard chemicals and prevent a complete wipeout of beneficials," he said.
The armyworm infestation is expected to continue through September and October and threatens hay fields and pastures. They should taper off as the weather changes and there is less food for them.
Environmental News Network |
