CLEWISTON -- The insects munching on some of the 3 million orange trees in the Southern Gardens Citrus groves looked real familiar to Tim Gast.

He knew he’d seen them somewhere before. Ah, yes: the Asian citrus psylla, Diaphorina citri, a small sucking insect he’d seen in China’s Guangxi province. Sure enough, it was the psylla, University of Florida entomologists confirmed, and it was running rampant in the groves.

Soon, tiny parasitic wasps raised in captivity by the university were on their way to Clewiston to be released in the groves to conquer the psylla.

It was all in a day’s work for Gast, citrus research horticulturist–a tree doctor of sorts–for the 28,000 acres of orange groves owned by U.S. Sugar Corp.

From 1997 to 1999, Gast worked in China, managing 7,000 acres of orange groves for a joint venture of Dole and Tropicana. After spending a year as an agricultural scientist at Tropicana in Bradenton, Gast joined Southern Gardens in March. Gast, 43, has worked in the citrus industry for 17 years.

Although some similarities are shared by groves in China and Florida, the way citrus canker is dealt with isn’t one of them.

In China, citrus canker, a debilitating bacterial disease that renders trees unproductive, is endemic. Growers try to live with it through management techniques. In Florida, removing infected trees and those within 1,900 feet has been the state’s way of fighting the blight for the past six years.

"Canker is the worst citrus disease I’ve seen," Gast says, recalling how quickly it spread in China during rainstorms and how control methods ultimately fail.

Gast, who has a master’s degree in plant physiology from the University of Arizona, probably is one of the few agricultural scientists in Florida who have worked with canker on a daily basis.

"Tim wasn’t hired just because he’s worked with canker, but it’s a plus," said Robert Buker, Southern Gardens’ president. "If we get canker, we wouldn’t be allowed to live with it. We would have to cut trees down."

Southern Gardens’ groves have no signs of citrus canker, but the disease has been found within 2 miles to the north, west and south. Under the state’s eradication program, 2 million residential and commercial citrus trees have been cut down.

In China, Gast says, the citrus-growing region on the country’s southeast coast has a warm, humid climate similar to South Florida’s . Growers there attempt to control the disease through copper and antibiotic sprays. Using those methods, the citrus canker in Gast’s Guangxi grove had been fairly well confined.

Then, disaster struck.

"In 1999, we had big blocks of trees that were free of canker. Then in July, it rained for 16 days straight," he said. ‘Within a couple of weeks after that, the fruit was covered with canker. There was nothing we could do."

Gast said the growers had spent 60 percent of their pest and disease-control budget on canker.

The canker’s spread varied from year to year, Gast said. In dry years, canker might affect less than 10 percent of the trees, but in a windy, rainy year, 50 percent of the trees could become infected.

"Then, the next year, those trees will support less fruit. It’s progressive," Gast said.

Typically, the Chinese deal with canker by letting the spring’s new growth bloom and grow into fruit because that’s the dry season. When the summer "flush" comes, and canker is likely to spread with the rain, laborers are hired to remove the new growth.

"They pay people 15 cents an hour to pick the summer growth off by hand, and they spray with copper like crazy," Gast said.

Gast supports Florida’s eradication program, although it’s not possible to predict the outcome yet. "If we give up on eradication, there won’t be any going back."

The alternative to eradication, living with canker, would be worse in a climate such as ours, because canker would spread rapidly, he said.

Meanwhile, Gast is battling other pests at Southern Gardens, and says spraying is not always the best way to manage insects. Pesticides can be expensive and can destroy beneficial bugs.

He’s basically a troubleshooter whose job is to assess quickly what can be done, whether there’s a new insect in the groves or a wilting tree.

Armed with simple tools such as a fruit knife and a 20-power hand lens, Gast drives the sandy groves in a four-wheel-drive pickup, scouting for insects an diseases.

"Most of the mites, insects and beneficial insects we are concerned with are tiny," Gast said.

But those tiny pests can quickly wreak havoc. Southern Gardens is producing more than 7 million 90-pound boxes of oranges this year, so a lot is at stake.

Gast works closely with the company’s four grove managers and researchers at U.S. Sugar to make sure the citrus pests are kept in check. Part of his job is to conduct field trials to determine where improvements can be made in fertilization, pest and disease control, irrigation and other practices.

With the continued globalization of agriculture, the incidence of new pests and diseases is increasing. The biggest tree-killer in the groves right now is a virus known as tristeza. First spotted in Southern Gardens’ groves four years ago, it’s spread by the brown citrus aphid, which comes from South America and the Caribbean, Gast said.

Whatever the pest being fought, the goal is to keep the trees as healthy and productive as possible. Despite the best efforts, about 1 percent of the groves' trees die from insects or disease each year, Buker says.

In coming years, Southern Gardens expects to use more and more technology, such as global information systems that track operations and pinpoint problems, Buker says. But no matter how big a role technology plays, people such as Gast still will be needed.

Said Buker: "There’s no substitute for the human eye, the human hand and the human brain."