Fruit drop in Florida’s orange groves rose dramatically this winter, and growers have their fingers crossed that it’s not a harbinger of things to come.

Meanwhile, theories are flying about what caused this unusual occurrence.

According to a February report from U.S. Department of Agriculture’s National Agricultural Statistics Service, Florida’s all-orange forecast was 141 million 90-pound boxes—down 9 percent from the initial October estimate.

Early, midseason and navel varieties in Florida were forecast at 66 million boxes, down 9 percent from October and down 10 percent from the 2011-12 season.

“Projected droppage is the highest since the 1969-70 season, while size is projected to be below average,” according to the report.

Numerous theories

Theories abound for the unusual degree of fruit drop. But most agree that huanglongbing—also known as HLB or citrus greening disease—has something to do with it.

Bob Ebel, citrus physiologist at the University of Florida’s Southwest Florida Research and Education Center at Immokalee, attributes the surge in fruit drop to “a confluence of factors.”

First comes widespread citrus greening, he says.

Next, stress from last year’s drought may have predisposed fruit to drop early, Ebel says. But a cool spell followed by a warming pattern may have had an even bigger impact than the drought, he says.

Once the rain did come, it promoted growth.

“Essentially, what we’re seeing is an acceleration of the maturity of the fruit, which is really undesirable,” he says.

Sugar content and acid levels also were lower than what growers like.

Stressful situation

Bob Rouse, an associate professor at the Immokalee research facility, agrees that “a multitude of stresses all at the same time” sparked the excessive fruit drop.

HLB is the prime cause and has added to the stress, he says.

Trees that showed no signs of greening only had fruit drop of 2 percent to 3 percent per month, he said.

Trees that were infected, yet otherwise healthy and productive, experienced drop of about 7 percent—twice as much as usual.

Infected trees with some decline had drop rates of 30 percent to 40 percent, compared with 10 percent to 15 percent during a normal year.

The Ridge area of Polk County seemed to have more severe drop than the southwest area, possibly due to extremely dry weather, Rouse says.

Two possibilities

L. Gene Albrigo, emeritus professor of horticulture at the University of Florid Citrus Research and Education Center in Lake Alfred, cites two possible causes. But he, too, says he believes citrus greening is the main culprit.

Every year, the number of infected trees rises, he says.

“This is the first year we have perhaps reached a critical number of these kinds of trees in enough groves and enough in each grove to see a statistical effect on yield,” he says.

The second possibility is the disease interacting with weather factors. In this scenario, fruit drop would decline in the future.

“I’m not very optimistic about the second being likely because the conditions didn’t seem to be favorable for excessive drop in general,” Albrigo says.

So far, there hasn’t been much growers can do to counter fruit drop.

Albrigo says attempts to use chemicals to reduce natural drop during the pre-harvest period this year were unsuccessful.

“They were probably put on too late,” he says.

Some chemicals, such as the herbicide 2, 4-D, which are labeled for other crops, may be relatively easy to get labeled for citrus, he says.

Ebel says he is not aware of any practical solutions at this point, although he says there’s a slight chance that starting fertilization programs earlier might help.

Economically speaking

From an economic standpoint, fruit drop may actually benefit growers, says Tom Spreen, professor emeritus of food and resource economics at the University of Florida, Gainesville.

“It means the prices are going to be stronger than what they would have been,” he says. “When they started reducing the crop [estimate], you could see the cash market prices begin to perk up.”

By the end of the season, “It probably is a wash or maybe some slight benefit,” Spreen says. “I think the growers will probably be OK in terms of returns.”

High drop rate

The Story Cos., a Lake Wales-based grower that owns or manages 6,500 acres, experienced abnormally high drop of early- and mid-season fruit, says vice president Kyle Story.

“It has had a dramatic effect on our overall operations,” he says.

Story estimates that between fruit drop and the smaller size of the fruit remaining on the trees, his company will be down almost 10percent in its early-midseason varieties compared with last year.

However, that may not be all bad news from a profitability standpoint.

“We’ve seen our cash market increase since the beginning of the season,” he says. “It hasn’t affected the bottom line a tremendous amount, but it’s been helpful.”

Hope for valencias

In early February, the forecast seemed promising for the upcoming valencia season.

Ebel says the earlier the valencia season ends, the less the effect of fruit drop probably will be.

“If it goes late, they could run into a problem,” he says.

Otherwise, “There probably will be some extra drop than what they’re used to, but hopefully, it won’t accelerate as the harvest season wears on.”

It’s hard to tell if valencias will experience much fruit drop, Rouse says.

The valencia season was expected to start early this year, with picking beginning in March.

If drop does occur, it most likely will be evident before April 1, he says.

Things were looking up volumewise for The Story Co. in early February.

“Luckily, thus far, we have not seen the late oranges—the valencias—follow suit [with the early-midseason varieties],” Story says. “We’re keeping a close eye on that on a daily basis in all parts of the state.”

Story was trying to remain hopeful.

 “The optimistic side of me wants to [say] that it’s just a one-time event,” he says. “But I don’t know that to be true.”

Concern at retail

There is some concern about orange juice movement at retail because supermarkets are reluctant to reduce prices to pre-hurricane levels, Spreen says.

“They’re not sure they’re going to have the fruit to be able to sustain higher movement,” he says.

Spreen says it’s a “bit of a chicken-and-an-egg problem.”

“If you’re worried about the supply, you’re not going to cut the price to get the movement going,” he says. “Yet that’s precisely what they need to do to get the movement going.”

Ebel is optimistic that increasingly health-conscious consumers will continue to buy orange juice, even at a higher price.

“Orange juice is a healthy drink, and people know that,” he says. “I think there will always be a market for it.”