When the citrus tree-killing disease known as greening was detected for the first time in the United States in Homestead, Fla., in August 2005, some feared the end was near for Florida’s signature industry.

Now, more than seven years later, the apocalypse has not occurred, but the disease that results in bitter, misshapen fruit is said to be present in every grove to some extent. Although no one knows the actual number of infected trees, many place it as somewhere between 40 to 70 percent.

The citrus industry has undergone a sea change. Production costs are up about 40 percent in many cases, mostly due to the cost of spraying for psyllids, the insects that spread the disease, and to nutritional programs to keep trees as healthy as possible.

Primarily through a grower-funded tax on each box of fruit, the citrus industry has invested $66 million in 129 research projects run by 30 doctoral scientists looking for a solution to the disease, also known as Huanglongbing or HLB.

“We understand the sense of urgency. We are going as fast as we can,” said Jude Grosser, a professor of citrus breeding and genetics at the University of Florida Citrus Research and Education Center in Lake Alfred. Grosser and others are working to develop disease-resistant trees, but breeding is a slow process.

“You have to pursue all the avenues. You don’t know which one the home run is going to come from,” said Grosser, who is optimistic a solution will be found.

The industry continues to shrink. The state’s commercial citrus acreage has shrunk to 531,493 acres as of the fall of 2012, a 28 percent decline from 748,555 acres in 2004. That’s the lowest since the U.S. Department of Agriculture began the survey began in 1966.

This season the USDA has revised the crop forecast downward twice since October, because the amount of fruit dropping from trees is greater than expected and the worst in more than 40 years. Growers are blaming greening and drought. In October the outlook was for 154 million 90-pound boxes of oranges, but the January estimate predicts a crop of 142 million boxes of oranges.

The grapefruit forecast has dropped to 18 million boxes from 20.3 million.

Tom Spreen, a professor emeritus at the University of Florida’s Institute of Food and Agricultural Sciences, said that growers are planting about half the number of new trees they would have planted if there were no greening.

“Going forward, the industry will be smaller,” Spreen said.

But, Spreen said, growers have come up with a whole new line of defense the doomsayers did not predict, which has allowed it to produce more fruit than it would have.

Young trees are babied in enclosed greenhouses to keep out the Asian citrus psyllid, a tiny insect that spreads the greening bacterium from plant to plant. Once they’re planted in the groves, the trees are sprayed to keep the psyllid population down.

“The total industry is working diligently to control the psyllid population, but the challenge is, the psyllid in Florida is as prevalent as the mosquito,” said Ricke Kress, president of Southern Gardens Citrus, a U.S. Sugar subsidiary south of Clewiston, Fla. Southern Gardens owns groves and has the only large orange juice plant in the southern part of the state, producing 80 million to 100 million gallons a year.

Southern Gardens has invested more than $6 million in research. It has planted the fourth generation of trees that contain two spinach genes that provide resistance to greening. The trees are developed in the lab by Erik Mirkov, a Texas AgriLfe Research plant pathologist in Weslaco, Texas.

The genetically modified trees and fruit will have to go through regulatory approval from the U.S. Food and Drug Administration, the Environmental Protection Agency and the USDA. Although more than 80 percent of such crops as corn, soybeans, canola and sugar beets are genetically modified, there’s increasing public concern about them.

“We have been meeting with the agencies since 2006. They know exactly what we are doing and how we are doing it,” Kress said. “We know we have a disease. We have to find a solution. When we find a solution, we know we will have to go through the regulatory approval process. We will also have to work through the consumer approval process.”

Once a disease-resistant tree is available, Kress said, many chemicals being used to control psyllids can be eliminated.

Although the prestigious National Academy of Sciences recommended three years ago that all infected trees be removed, most growers are no longer doing so, except for the largest growers.

Southern Gardens has taken out approximately 650,000 trees identified as infected, Kress said, roughly 25 percent of the grove now at 1.8-plus million trees. It has planted more than 363,000 trees in the past four years.

Pete Spyke, president of Arapaho Citrus Management in Fort Pierce, Fla., said Florida growers missed the window of opportunity when tree removal might have worked. Since everyone was not removing trees, the infection continued to spread.

Those who waited too long would have been out of business because they would have had to remove every tree.

“They did not do that. That doomed the rest of us to living with it,” Spyke said.

Spyke, who produces citrus for the fresh fruit market, believes in a system he is using called open hydroponics. It delivers a constant supply of water and nutrients to the trees through drip irrigation.

“Trees come into production sooner and produce higher quality fruit. You get more fruit, and it costs you less money,” Spyke said.

Doug Bournique, executive vice president of the Indian River Citrus League in Vero Beach, Fla., said, he’s encouraged by a spurt of citrus planting.

“Even with the disease pressure, people are realizing they can keep the tree prosperous for 10 to 12 years with the prices they are receiving. The prices are good enough to cover the high cost of production,” Bournique said.

The goal is to keep the industry viable until resistant trees are developed, said Bournique, who spends the majority of his time seeking funding and support for research.

Although some citrus growers have turned to producing landscape trees, peaches or other products, or sold their groves, a tough bunch of growers is keeping at it.

“We are not diversifying,” Dan Richey, president of 4,000-acre Vero Beach-based Riverfront Groves, a major grapefruit producer, said. “We believe the future is in citrus. We are staying the course. We seem be getting a larger piece of a shrinking pie.”

Kress agrees, “Those that want to be in business are going to be, and those that don’t, won’t be. People will adapt. In agriculture, the only consistent thing is the inconsistencies. Florida orange juice is not going to go away.”

With greening found in the citrus-producing states of Texas and California for the first time in 2012, the regions are sharing information.

“My message to California is when you see that tree with that yellow branch, you have to take it out,” Spyke said. “We lost our ability to make the better choice. We didn’t react quickly enough.”

Citrus greening disease

What it is: A bacterial disease known as Huanglongbing (HLB) or yellow dragon disease, it is one of the most serious citrus diseases in the world, killing trees.

Its origin: Farmers in Southern China first noted the presence of the disease in the late 1800s.

Florida history: In 2005, U.S. Department of Agriculture scientists confirmed the first U.S. detection of greening on samples of pomelo leaves and fruit from a Miami-Dade County grove. It is now endemic to Florida and found in every citrus-producing county.

Symptoms: Yellow shoots, mottled leaves, twig death, tree decline and reduced fruit size and quality. Affected fruit tastes bitter, medicinal and sour. Symptoms don’t show up for an average of two years following infection.

How it’s transmitted: Asian citrus psyllids, first found in the United States in Delray Beach, Fla., in 1998, transport the greening pathogen from infected trees to healthy trees as they feed on the plant. They have mottled brown wings and sit at an angle to the shoot or leaf on which they feed.

The cure: None

Source: U.S. Department of Agriculture Animal and Plant Health Inspection Service