Published on 12/01/05

'Buggy year' costs Georgia farmers

By Brad Haire
University of Georgia

Damage from insects and caterpillars can vary yearly in most Georgia crops. University of Georgia experts say this year will go down as a buggy one.

Crop-eating bugs like Georgia's subtropical climate, says Steve Brown, a UGA Cooperative Extension entomologist.

Peanut pests

Georgia peanut farmers usually don't spray for foliage-feeding insects, Brown said. But this year was different. Some growers had to spray two or three times.

The three-cornered alfalfa hopper caused most of the problems, reducing yields in some fields. This stem-eating bug wasn't much of a problem a decade ago.

Peanut farmers apply an insecticide in the furrow with seeds at planting time to protect against thrips. These tiny insects feed on leaves and can carry the tomato spotted wilt virus. This year, thrips showed up later in the spring anyway. The yield loss to TSWV is expected to be 7 percent, the worst in a decade.

Estimates for the cost of control and damage from pests aren't available yet for 2005, Brown said. But peanut pests cost Georgia farmers $14.3 million in 2004. And the cost to the state's 750,000-acre crop is expected to be higher this year.

Cotton critters

Cotton pests cost Georgia farmers $102 million in control measures and losses this year. About $84 per acre. That's 15 percent more than last year, said Phillip Roberts, a UGA Extension cotton entomologist.

Farmers sprayed about 20 percent more for cotton pests this year than last, Roberts said. They sprayed mostly to control stinkbugs, now a major pest in Georgia cotton.

In 2003, farmers lost about 72,000 bales of cotton to stinkbugs. They grew 2.1 million bales (roughly 480 pounds of lint) that year. This year, they'll lose about 44,000 bales while producing 2 million.

"The reduction in damage is primarily due to our growers now understanding the problems stinkbugs cause and ... doing a good job managing them," Roberts said.

About 90 percent of Georgia's 1.21 million acres of cotton is planted in Bt cotton. This cotton has a gene that lets the plant produce a toxin from the bacterium, Bacillus thuringiensis. The toxin kills many caterpillar pests.

Before Bt cotton became available in the mid-1990s, Georgia farmers sprayed insecticides about five times per year. They averaged three times this year. Back before boll weevils were eradicated, farmers had to spray about 20 times a year.

Corn earworms damaged cotton in Georgia and other states, too. Bt cotton controls this worm, but not completely. The caterpillar feeds and grows inside cotton flowers, where the toxin isn't as strong. When it moves to feed on developing bolls, where the toxin is stronger, it's not easily killed.

Farmers spray pyrethroid insecticides to kill them when they get out of control. Many worms survived this year, Roberts said. It isn't completely clear why they did. But Roberts and scientists in other states are studying the problem.

Veggie villains

Stinkbugs are hurting Georgia's $700 million annual vegetable crop, too, said Stormy Sparks, a UGA Extension vegetable entomologist. Their piercing bite can damage forming fruit. And damaged fruit can't be sold. The industry is looking for ways to control it.

Georgia farmers grow about 30 kinds of vegetables, such as peppers, sweet corn, tomatoes and eggplant. Because of the crops' high per-acre value and consumers' intolerance of insect damage, farmers spray to protect the crops.

Spring sweet corn can be sprayed as much as 20 times during its growing season. At times during the critical silking stage, it's sprayed twice a day. Tomatoes often need spraying weekly.

Farmers minimize insecticide use by growing most crops when pest populations are low, Sparks said. Still, insects cost vegetable farmers about $57 million in 2004.

This year will likely cost as much or more. "I'd say, all in all, it was a buggy year," Sparks said.

Brad Haire is the former news editor with the University of Georgia College of Agricultural and Environmental Sciences.