With bacteria-induced greening (also known as Huanlongbing) claiming more and more of the state’s citrus crops each year, some Florida growers are turning to thermotherapy to limit bacterial growth and improve production.Mike Houghtaling of Dooley Groves, a Tampa Bay-area pick-your-own farm with more than fifteen different citrus varieties, is one such grower. A lifelong citrus grower, Houghtaling planted about 8500 trees in 2011 and quickly saw the effects of greening.
“It went from nothing the first year, to just the occasional tree in the second year, to 10% [of trees affected] in the third year, and then 20% to 30% this year.” Houghtaling notes that his biggest crop, Mineola Tangelos (also known as Honeybells), is one of the most susceptible varieties to citrus greening, which may have contributed to the quick spread of the disease.
Worried that his entire grove would be affected within two years’ time, Houghtaling decided to try thermotherapy, a method that has been shown to reduce greening bacteria in research performed by the USDA and the University of Florida’s Citrus Research and Education Center.
Technique uses heat to kill bacteria
To treat his groves, Houghtaling turned to ScoringAg-Pro’s TreeSteamer©, a thermotherapy rig designed specifically to combat citrus greening. Thermotherapy devices like the TreeSteamer© work by covering an object – in this case one to three citrus trees – in a canopy, then releasing steam within the enclosure. The steam then heats up the space inside the canopy, and when used on citrus trees, this level of heat helps kill greening bacteria.
Houghtaling, who began using the TreeSteamer© in August and spent one month treating affected trees, says that he believes the treatment has delivered results. “My trees have responded,” Houghtaling says with a slight laugh, “by not getting worse.”
“In previous years, going into the winter, our trees would look progressively worse, where we’d see a lot more discoloration and dropping fruit,” Houghtaling elaborates. This year, he says, that isn’t happening.
What’s more, Houghtaling says that his greened fruit tastes much sweeter this year than it did last year. While Houghtaling is quick to point out that the improved eating quality could be a lucky anomaly, he notes that increased sweetness is in keeping with published research by the USDA and the University of Florida.
Fuel, labor biggest investments
After his first year of thermotherapy, Houghtaling says that fuel and labor proved the most significant costs.
The TreeSteamer© uses a diesel generator for power, which runs through 6.5 gallons of fuel per hour. With diesel averaging $2.90 per gallon this summer, Houghtaling spent $18.86 in diesel on each hour of thermotherapy he performed. Houghtaling says that he was able to treat approximately sixty trees each hour – twenty separate treatments at a rate of three trees per treatment – putting his fuel cost per tree just north of 30 cents. (Houghtaling notes that diesel prices have since fallen; were he to treat his groves now, his fuel cost per tree would be closer to 22 cents.)
Beyond fuel, Houghtaling says that labor is the most significant cost. This is due to pre-treatment trimming and operation of the TreeSteamer© itself. Houghtaling notes that only one person is required for proper set-up and operation of the machine.
Houghtaling says that he will need to wait before he has hard numbers to assess the full benefits of thermotherapy on his orchards, but says that early results have him hopeful. “At this point, I’m signing on for treatment once a year.”
For more information:
Mike Houghtaling
Dooley Groves
Tel: +1 (800) 522-6411