By SUSAN SALISBURY

Palm Beach Post Staff Writer

Monday, December 17, 2007

CLEWISTON — In a citrus grove so peaceful and remote that a group of five deer has just been spotted, Mary Weston is working to identify a killer disease.

After a close-up look at an orange tree's mottled leaves and yellow veins, she knows she's seeing once again the telltale signs of greening disease. Weston quickly sprays its trunk with blue paint, marking the tree for destruction.

Mary Weston, who has worked at Southern Gardens Citrus for 25 years, tags a tree infected with greening by spray painting it blue. Weston, a senior scout, is called in to check on trees marked by scouts to make sure they are in fact infected with greening.

A bulldozer dumps orange trees infected with the citrus greening disease onto a burning pile at a Southern Garden Citrus' grove. The infected trees are located by scouts, confirmed by a senior scout and marked, then remvoed, and then burned in a large pile in hopes of not spreading the disease.

"We look for greening every day," said Weston, 49, a senior scout at Southern Gardens Citrus, west of Clewiston in Hendry County.

Her experienced eye confirms the finds initially spotted by other scouts. She notes the location - "J block, Zone 57" - and enters it in a computer kept in the "mule," the golf cart-type vehicle she drives.

Greening, also known by its Chinese name of huanglongbing, or yellow dragon disease, is one of the most feared maladies in the citrus world.

Believed to be native to China, the disease first was confirmed in the United States in August 2005, when it was found in Miami-Dade County.

By October of that year, it had been found in a grove of Southern Gardens, Florida's third-largest citrus grower, which last season processed 115 million gallons of orange juice.

Since then, the company's grove-care costs have risen 35 percent to 40 percent, mostly because of greening surveys, tree removal and chemicals used to control the Asian citrus psyllid, the exotic insect that spreads the disease, said Ricke Kress, president of Southern Gardens.

Weston is one of 43 people walking in Southern Gardens Citrus' three groves, searching for the bacterial disease, which causes trees to produce small, misshapen fruit and eventually become unproductive. The trees will be taken out and burned.

An additional group of four scouts searches for nothing but the psyllid.

Their job is to check each tree four times a year.

That's no easy task, with 16,500 acres of 2.3 million orange trees spread out over a 10-by-30-mile area in southern Hendry County. Each scout covers 6 to 15 acres a day.

Southern Gardens instituted its plan immediately after the disease was found in its grove, even though little was known in this country about greening. The company moved forward based on what was known about the disease in Brazil, China and other countries.

"We couldn't wait for the research to be done," said Kress, 56. "We made the decision we were going to be proactive and learn at the same time."

Finding and removing the infected trees is an expensive and serious business, said Jim Snively, the company's vice president for grove operations.

In the past two years, approximately 180,000 of Southern Gardens' trees - about 4 percent - have been removed because of greening.

"The big challenge is finding positive trees and getting them removed in a timely fashion," Snively said.

Standing in the grove, Snively, 44, cuts an orange to check for aborted seeds, which he finds right away.

Shrunken and brown, the seeds sit inside a lopsided, unhealthy fruit.

"This tree is collapsing and going downhill because of greening," Snively said, indicating its mottled leaves and yellowed veins. "It has dropped a lot of leaves. These are classic symptoms."

'Eradicate the psyllid'

Snively said the company's spray-program costs have risen to $254 an acre, or $4.2 million a year, from $80 an acre a few years ago, with most of the increase attributable to greening.

The psyllid is a "flying hypodermic needle" that injects the greening bacterium into trees one at a time, Snively said, and that's why he favors eliminating the bug to get rid of the disease.

"Some people think we need a greening-resistant tree. I say eradicate the psyllid," he said. "We can't have greening without the psyllid that spreads it.

"We can never control the psyllid with chemical controls. It will require some sort of biological control, such as a disruption in the way they reproduce."

Some $8 million in greening and citrus canker research, amounting to more than 80 state and federal projects, is under way.

Harold Browning, director of the University of Florida's Citrus Research and Education Center in Lake Alfred, said many of the projects are new efforts and just now are getting started.

"We have not experienced any breakthroughs that allow us to discuss solutions at this point," Browning said.

Pasco Avery, a UF microbiologist and entomologist based in Fort Pierce, is part of a team looking into a fungus that kills psyllids. He envisions surrounding the groves with some sort of barrier to stop the bugs in their tracks.

"From an ecological standpoint, it makes a lot of sense," Avery said. "We have to try and bring back the psyllid's natural enemies."

Beginning today, the U.S. Department of Agriculture's Animal and Plant Health Inspection Service will hold a two-day summit in Bethesda, Md., to discuss citrus greening. Florida citrus industry representatives, state and federal officials, and researchers from Texas and California are expected to attend the meeting, which will be closed to the media.

Abandoned groves a big issue

While growers await a better solution, they continue to spray pesticides to control the psyllids and remove infected trees. But their efforts are thwarted by neglected and abandoned groves.

One such grove is across County Road 835 from Southern Gardens.

"They are not removing trees. They aren't treating for psyllids. The (disease) is sitting there," Snively said, gazing at the offending grove.

Unlike with canker-infected trees, which the government removed from homeowners' properties and commercial groves during an unsuccessful 11-year eradication program that ended last year, there's no requirement that greening-infected trees be removed.

Doug Bournique, executive vice president of the Indian River Citrus League in Vero Beach, said an industry committee working with the Florida Department of Agriculture's Division of Plant Industry is discussing the legal and political options for dealing with abandoned groves.

"It's a big issue," Bournique said. "There are growers who have kept groves barely alive."

The problem is worse in Martin, St. Lucie and Indian River counties, where developers, as well as the South Florida Water Management District, have purchased groves but have done nothing with them, he said.

"Greening is starting to show up at an accelerated rate," Bournique said.

Kress, Snively, Bournique and others agree that industry representatives must work together to control greening.

"It will require a regional effort," Bournique said.


Source: http://www.palmbeachpost.com/business/content/business/epaper/2007/12/17/m1bz_greening_1217.html