Supercharged mixture — Nutrition tweaks out-maneuver citrus disease threats in DeVane groves

The Florida Department of Agriculture and Consumer Services initially ordered all trees destroyed within a 1,600-foot circle of a canker outbreak. After the disease spread widely, that was no longer practical.

As Jason DeVane drives a pickup truck through his family’s citrus groves near Fort Meade, Fla., he keeps an eye peeled for troubled trees.

“There’s one and there’s one and there’s another one,” he says, bumping down a grove lane. “See the yellow tint on the leaves and how some of the leaves are mottled? See the twig dieback?”

He’s looking for trees attacked by citrus greening disease and doesn’t have to go far to find them. A 160-acre block of trees here was one of the first in the area verified with greening disease as well as citrus canker. Both diseases promised to be devastating to the Florida citrus industry. DeVane, though, along with some other growers, found ways to live with them rather than destroy the diseased trees.

Greening disease, which DeVane terms the bigger threat to his trees, inhibits the flow of nutrients and water in the tree’s xylem and phloem. Spread by a tiny exotic vector, the Asian citrus psyllid, as it feeds, the disease basically starves trees.

As the disease became more widespread after being found in 2005, DeVane began paying attention to the theories of Maury Boyd, a citrus grower based in Winter Garden, who applies a super-charged mixture of nutrients and chemicals in foliar sprays to help trees withstand the disease.

That idea, a bit controversial at first, became credible after University of Florida citrus scientists Robert Rouse and Tim Spann studied it and called it a viable option for groves hard-hit by greening.

“Maury threw the whole kitchen sink at his problem and it worked. Dr. Rouse looked at it in research at Immokalee and saw good results from a really aggressive nutritional program,” DeVane says.

That encouraged DeVane to step up nutrition in his groves. Prior to using this approach, he made three ground applications of dry fertilizer yearly. Now he’s applying ground applications six times a year in addition to two ultra low volume dormant sprays.

He applies N, P and K, and, in addition, gets micronutrients in two formulations of KeyPlex. KeyPlex 1200 contains magnesium, sulfur, boron, iron, manganese, molybdenum and zinc, along with alpha-keto acids and humic acid. KeyPlex 1400 has those same acids and includes N with iron, manganese and zinc.

The trees get a prebloom spray followed by a postbloom application, then others in early May, June, July-August, November and January-February.

“A sprayer or fogging machine is pretty much out there all the time now for a lot of the year. We do have to pay to attention to a pre-harvest time restraint with insecticides we use in the mix,” DeVane says.

So far, this program keeps trees producing fruit but also greatly increases costs. Prior to the greening disease problem, DeVane’s caretaking costs averaged $800 an acre. Now that runs as high as $2,000 an acre.

“It’s $1,600 if you just do the minimum. Production cost has at least doubled but the thing is, those trees are still producing fruit. We haven’t had to push them up and reset,” DeVane says.

“What we’re doing is not a cure for greening but it is buying time and prolonging the life of the tree. Our goal is to still have a somewhat healthy tree that puts on a crop of fruit even if it does have the disease. A combination of variety and rootstock resistance is the long-term answer. Short-term, though, this is helping us get by with the disease.”

A similar philosophy seems to work on trees with citrus canker, which DeVane thinks blew into the area from South Florida on Hurricane Charley in 2004, one of four hurricanes that hit the state during a six-week period that year.

“The first outbreak of canker was in the Miami and Palm Beach County areas. After Hurricane Charley, on the ridge here we had an explosion of it. When that canker spore explodes, it’s as volatile as cigarette smoke. It can ride on the wind,” he says.

The Florida Department of Agriculture and Consumer Services initially ordered all trees destroyed within a 1,600-foot circle of a canker outbreak. After the disease spread widely, that was no longer practical. “We wouldn’t have a citrus industry if they’d kept doing that. We had to learn to live with it,” DeVane says.

DeVane now applies copper to help with the canker problem. “Before canker hit, we weren’t spraying copper and we lost just about all the fruit on those trees by harvest. Now in the worst canker block, I spray copper every 21 days from quarter-size fruit up to almost picking time,” DeVane says.

“We have a high amount of inoculum in that block of trees. We still have canker. It’s going to be there. But we can live with it as long as these practices make it economical to produce fruit. We’re trying to avoid pushing up trees.”

A fifth-generation Florida citrus grower, DeVane’s family now owns 1,835 acres of citrus and manages another 500 acres. Their groves range across Polk, Hardee, Manatee and Hillsborough counties. They also operate a citrus harvesting business started in 1976.

His grandfather, Floyd, and father, Kenny, are still active in the family operation. His 29-year-old brother, Derek, manages the harvesting and picking crews. Another brother, Kyle, works in the company office.

Jason DeVane, 35, joined the family business in 1999 after graduating from Florida Southern College with a major in marketing and minor in citrus production. Before heading to the home place, he worked as harvesting coordinator for W.G. Roe and Sons, a grower/packer/shipper in Winter Haven, for 1-1/2 years, following several college internships with crop protection companies.

His wife, Olivia, came from a family that also operated a citrus harvesting business. He’s hoping their four children ranging in age from two to seven, might someday have the opportunity to work in the family groves, too.  Despite the industry’s problems, he thinks the future for the orange juice business looks promising.

“We’re pretty much out of fresh fruit and devoting everything to juice. If you think about where the industry has been, there have been a lot of problems. We’ve had leaf miner, weevils, brown citrus aphid. We’ve had hurricanes. We’ve had freezes. Now we have new obstacles, canker and greening. But I don’t see anybody throwing in the towel because of that. We got past those other problems. We can get past this, too,” he says.

“To succeed in this industry, we have to be committed. We have to do whatever is necessary as an industry to handle these things. We need to band together and support research. We need to get a long-term solution to the greening problem. I do think we’re getting pretty close to a solution but it’s going to take a while to go through the research and development process,” he says.

He likens the current situation to the 1980’s and 1990’s when citrus tristeza virus was killing trees on sour orange rootstock.

“In a ten-year period in our groves, we completely replanted that sour orange rootstock. So, we’ve done it once. If that’s the solution, we can do it again. It’ll be expensive but we’ll do what we’ve got to do as long as citrus is a profitable crop,” DeVane says.

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