Florida Citrus Grower Keeps His Cool In The Heat Of HLB

Rex Clonts puts his mechanical skills to work gained growing vegetables to construct a thermotherapy system for citrus. Photo by Frank Giles
Rex Clonts puts his mechanical skills to work gained growing vegetables to construct a thermotherapy system for citrus. Photo by Frank Giles

About 15 years ago, Rex Clonts got out of the vegetable growing business after many years to “retire to the easy life” of a citrus grower. But, the onslaught of HLB has turned the easy life on its ear and requires management more akin to row crops these days.

Years as a vegetable grower taught Clonts mechanical skills, which he hopes will serve him well trying to grow citrus in the presence of HLB. He is putting those skills to work to create a viable and systematic approach to utilize thermotherapy for treating HLB-infected trees in his grove — literally heating HLB-infected trees up to 130°F.

Dr. Yongping Duan, a researcher at Ft. Pierce’s USDA Horticultural Lab, is among those studying thermotherapy as a means of killing the HLB bacteria in citrus trees.
“I went down to visit Dr. Duan to learn about his research and then went back to my experience in making machinery that we used to grow and harvest vegetables,” says Clonts. “There are growers out there trying heat therapy, but nobody is trying to design a system that can be used industry wide on all-sized trees.”

Rex Clonts Photo by Frank Giles
Rex Clonts Photo by Frank Giles

Clonts says his goal is to build a system capable of treating 100 of his acres per summer with a crew of no more than four people. The setup would include a string of tent structures capable of treating an eighth of a mile (600 to 650 feet depending on grove layout). In Clonts’ grove, that would take 26 modules covering 52 trees.

“If this is ever going to be adopted by the industry, it must be simple and systematic,” says Clonts. “It needs to be predictable enough that when the four-man crew shows up in the morning, they know exactly what their duties are for the day and can go perform them efficiently. And, everything I am using to build these tents is commercially available materials sold for greenhouse production.

“Using this very systematic approach, you would operate enough of these units to treat a third of your acres per year. The theory is the heat treatments provide positive benefits to the tree for two to three years. If you are treating a third of your acres per year, by the fourth year, you would be starting back over as the benefits begin to wear off.”

Another key to the system is the ability to treat large trees, which require much larger tents than what many growers have seen in action to date with smaller trees. Clonts has built two prototypes and a third is planned, which will be slightly smaller and easier to manage. Clonts gable-cut tops his trees at 12 to 14 feet, so the tents must be sized large enough to accommodate the height.

Time And Temperature

Clonts began actively treating his grove in June. The goal is to capture solar energy in the tents and maintain temperatures at 105°F to 130°F, which research shows will kill the HLB bacteria.
“Right now our rule of thumb is we keep the structure over the trees for three days, seeking 10 hours per day of temperatures more than 105°F,” says Clonts. “One of the big things we’ve learned is the heating is very different over these mature trees than if you just put the tent out over a grass field.”

The canopy and moist soil surface have a moderating effect on the temperatures inside the tent, making air circulation critical to the process. Clonts fixed this challenge by installing circulating fans in the tops of the tents to move air.

“In these big structures, if you don’t move the air with the fans, you are going to only heat the top of the tree and possibly damage it, and the bottom canopy is never going to get heated,” he says. “We are finding that one fan per tree in the structure takes care of this problem.”

To ensure temperatures are monitored correctly, three standard digital thermometers are placed inside the tent at two feet, six feet, and 12 feet in the canopy. When temperatures get too hot, a thermostat in the structure engages an automatic venting system.

“The automatic venting system is counter-intuitive because we have a motor that keeps the vents sealed until we hit the critical temperature of 130°F,” Clonts says. “When it hits the temperature, the motor shuts off and the vents open. We do this because we want the tents to self-vent if we lose power. When the temperature drops back to 125°F, the motor starts back up and closes the vent.”

Topics: , , , ,

Leave a Reply

One comment on “Florida Citrus Grower Keeps His Cool In The Heat Of HLB

  1. Three years of positive results ( doubling the yields & increasing the solids count ) has proven that treating severely infected trees with all natural, non-toxic Quantum Growth would be a lot cheaper method using the thermotherapy approach.

Citrus Stories
Port Tampa Bay shipping channel
Citrus
May 24, 2016
Panama Canal Expansion To Bring Trade Opportunities To Florida
Agriculture Commissioner Adam Putnam says a confluence of events is putting the state's producers in a good spot to open new markets. Read More
anti-GMO corn spoof via social media
Citrus
May 24, 2016
Social Media Posts On GMOs Falling Flat [Opinion]
Hopefully, the hysteria the West has perpetuated on genetic engineering will not stifle the potential of moving our production forward enough to help feed a growing global population. Read More
non-gmo label leafy greens
Citrus
May 24, 2016
Report Says GMOs Offer No Risk To Human Health
The study stresses the need for proper resistance management, the need for a different ways to evaluate all new crop varieties, regardless of process in which they were developed. Read More
Florida Ag Commissioner Adam Putnam checks out prepared school lunches. School meals are looking more colorful these days as fresh produce finds a place on the tray.
Citrus
May 24, 2016
Full-Time Effort Required To Feed Farm-To-School Programs
Florida Commissioner of Agriculture Adam Putnam gives a shout-out to those providing fuel to kids during the school year as well as the summer months. Read More
Photo credit: USDA
Citrus
May 23, 2016
World Health Organization Experts: Glyphosate Not Carcinogenic
Risk unlikely when consuming crops treated with herbicide. Read More
Food safety meeting for growers in Florida
Citrus
May 23, 2016
Florida Growers Putting Food Safety On Front Burner
Specialty crop industry stakeholders hungry to understand what’s ahead as FDA begins implementing new food safety rules. Read More
Participants of a Citrus Health Roundtable hosted by Yara International pose for a post-event photo.
Insect & Disease Update
May 20, 2016
Yara International Pledges $100,000 To Support Florida Agriculture Students
Scholarship will fund University of Florida undergraduate and graduate students. Read More
The Latest
Citrus
May 25, 2016
Monsanto Says Bayer Bid ‘Financially Ina…
Proposal cited as undervalued, not able to address financial, regulatory risks. Read More
Citrus
May 25, 2016
NRCS Invests $4.3 Million To Combat Clim…
The Natural Resources Conservation Service in California is committing funds to help farmers and ranchers mitigate the effects of climate change and help to reduce greenhouse gas emissions. Read More
Citrus
May 24, 2016
Panama Canal Expansion To Bring Trade Op…
Agriculture Commissioner Adam Putnam says a confluence of events is putting the state's producers in a good spot to open new markets. Read More
Citrus
May 24, 2016
Social Media Posts On GMOs Falling Flat …
Hopefully, the hysteria the West has perpetuated on genetic engineering will not stifle the potential of moving our production forward enough to help feed a growing global population. Read More
Citrus
May 24, 2016
Report Says GMOs Offer No Risk To Human …
The study stresses the need for proper resistance management, the need for a different ways to evaluate all new crop varieties, regardless of process in which they were developed. Read More
Citrus
May 24, 2016
Full-Time Effort Required To Feed Farm-T…
Florida Commissioner of Agriculture Adam Putnam gives a shout-out to those providing fuel to kids during the school year as well as the summer months. Read More
Citrus
May 23, 2016
World Health Organization Experts: Glyph…
Risk unlikely when consuming crops treated with herbicide. Read More
Citrus
May 23, 2016
Florida Growers Putting Food Safety On F…
Specialty crop industry stakeholders hungry to understand what’s ahead as FDA begins implementing new food safety rules. Read More
Citrus
May 20, 2016
Florida Farmland Becoming Big Deal For I…
Real estate values in the Sunshine State dictated by money looking for a home. Read More
Citrus
May 19, 2016
Bayer Makes Bid For Monsanto
Monsanto says proposal is being reviewed by board of directors as well as legal and financial advisors. Read More
Citrus
May 17, 2016
$130 Million In Funds For Fruit And Vege…
USDA allocates funds for Extension, organic production, food safety, and technology grants. Read More
Citrus
May 17, 2016
Border Protection Intercepts New Leafhop…
First of its kind found in European shipment. Read More
Citrus
May 16, 2016
3 New Herbicides For Florida Farmers To …
Trio of unique crop protection chemistries beckoning growers to whack weeds with these. Read More
Citrus
May 10, 2016
California Citrus Industry Leaders Slam …
Proposal “defies logic,” because growers are already worried about being ravaged by citrus greening, says California Citrus Mutual. Read More
Citrus
May 10, 2016
Winning Streak Continues For Florida Ora…
Updated crop estimate from USDA reveals uptick for third month in a row. Read More
Citrus
May 10, 2016
Survey: Beekeepers Lost 44% Of Bees Last…
Responses indicate summer losses rival winter losses for second year in a row. Read More
Citrus
May 4, 2016
$6 Million Available For Antimicrobial R…
Program to develop strategies to reduce public health risks in food chain. Read More
Citrus
May 3, 2016
New Program Targets Abandoned California…
Bayer and California Citrus Mutual have teamed up to help protect the state’s commercial citrus industry from deadly citrus greening. Read More
[gravityform id="62" title="false" description="false"]