Published on 11/08/07

Whitefly swarms swat Georgia tomato crop

By Brad Haire
University of Georgia

A disease carried by whiteflies has caused major troubles for Georgia tomato growers this fall. The tiny, prolific insects wiped out entire fields in some areas, says a University of Georgia vegetable specialist.

Whiteflies thrive in warm, dry weather. They had plenty to enjoy in Georgia this summer, said David Langston, a UGA Cooperative Extension plant pathologist. Whiteflies damage tomatoes and other crops by sucking the juice from leaves and stems.

But the tomato yellow-leaf-curl virus they carry caused more damage this fall, he said. TYLCV shuts down young plants and forces mature ones to drop fruit.

“The higher the whitefly pressure, the higher the incidence of tomato yellow-leaf-curl disease,” he said. “It’s pretty much that simple. And this year we had the highest population we’ve had in a decade, if not ever.”

Farmers in south-central Georgia had several hundred acres of tomatoes wiped by the disease, Langston said — virtually all of the crop there.

Fortunately, half of Georgia’s estimated 3,500 acres of tomatoes grow in Decatur County in southwest Georgia. Whitefly infestation was high there, too. But the disease appeared later in the growing season, affecting 10 percent of the crop, said Mitchell May, the UGA Extension coordinator in Decatur County.

Whitefly numbers can spin out of control in south Georgia, Langston said, where vegetables and cotton are grown near each other. Whiteflies like cotton, too.

A female whitefly can easily produce 300 or more offspring. In seven to 10 days, the females from that hatch can produce another 300 or more. In some small towns this summer, swarms looked like snow flurries.

Georgia farmers deal with sporadic outbreaks of the virus every year. In years with lower whitefly numbers, farmers can use insecticides to protect tomatoes and vegetables. “But this year, it wouldn’t have helped because of the massive number,” Langston said.

Farmers may have some TYLCV-resistant varieties to plant in the near future, Langton said. But until then, they can do little to fight the disease during a year such as this.

Georgia has a subtropical climate that allows farmers to grow two warm-season vegetable crops, such as tomatoes, peppers, squash and green beans, every year. They plant in the spring to harvest in the summer. Then they plant again in the summer to harvest in the fall. The tomato crop planted last spring did OK.

On a good year, farmers will harvest around 36,000 pounds of tomatoes per acre. The Georgia crop was worth $77 million last year.

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