Dundee Citrus invests heavily in citrus under protective screens

 Dundee is growing hundreds of acres of citrus under protective screens in Florida, each accounting for about 10 to 15 acres each. The growing method keeps out psyllids that spread citrus greening and allow for production to be ramped up faster than in traditional orchards.
Dundee is growing hundreds of acres of citrus under protective screens in Florida, each accounting for about 10 to 15 acres each. The growing method keeps out psyllids that spread citrus greening and allow for production to be ramped up faster than in traditional orchards.
(Dundee Citrus)

You may not have heard about Florida citrus being produced with the CUPS that's Citrus Under Protective Screens — method yet.

But, considering the investments made by the Dundee Citrus Growers Association and others, there is no doubt you soon will.

Seeking a sustainable path for commercial citrus production in a state fighting citrus canker and citrus greening disease, the choice to grow citrus under massive screen structures has emerged as a high-stakes bet on the future.

Steven Callaham, CEO at the Dundee Citrus Growers Association, Dundee, Fla., said Dundee followed the work that Dr. Arnold Schumann, with the University of Florida Citrus Research and Education Center at Lake Alfred, Fla., started doing with screens back in 2014.

At the time, Schumann had a one-acre protective structure where multiple experiments were conducted.

“We felt that, if you want to be able to grow high-quality, fresh fruit in an endemic greening environment, as we are in Florida, you have to think outside the box, and maybe look at some nontraditional means of accomplishing that,” Callaham said. 

The results that Dundee Citrus Growers Association saw from Schumann gave the group the confidence to take its efforts to a commercial level. Importantly, the CUPS method can prevent psyllids that spread citrus greening from entering the grove.

The Dundee Citrus Growers Association’s first project with CUPS broke ground back in 2017, Callaham said. The first trees in phase one were planted starting in late 2018. 

Those 3-year-old trees are flourishing, he said, growing extremely fast and producing high-quality fruit.

“We saw what was taking place there, and we developed a second phase,” he said.  The company's first phase consisted of 110 acres under-screen. The next year, Dundee developed another CUPS method phase with 113 acres, followed by another phase with 72 acres.

Now, with about 300 acres total under-screen, the protected trees are growing much faster than they would in a traditional outdoor setting, he said.

“They produce a large volume of fruit, bigger fruit size, cleaner, higher-quality fruit, and so you can really ramp up volume and production quite quickly with that,” Callaham said. “We’re very, very optimistic about it. I think, for our organization, it's going to be a very large piece of what of our fruit volume is in the future.”

In fact, Dundee Citrus will be breaking ground in late August on another project that will eventually put more than 600 acres under protective screen, he said, noting that “it's a major, major expansion for us." In addition, two of Dundee’s existing members have some citrus under protective screen. 

“What it looks like for our organization is, over the next three years, we're going to end up with close to 1,000 acres under-screen,” he said. Citrus varieties grown under-screen include mostly dark, red grapefruit, but also mandarins. Those varieties are what seem to be thriving in the CUPS environment.

The screens are opaque enough to see through, but appear white on the outside, he said. 

“You can see that there are trees behind it, but you can't really detect a lot of detail in there," he said. "The anti-insect screen doesn’t keep the smallest of insects out, but it keeps out the Asian citrus psyllid, which is our primary concern that vector of citrus greening."

Built tough

Callaham said the CUPS structures are engineered and manufactured in Spain, using galvanized steel frames and steel cables.

“It’s a very, very well-engineered, well-put together structure," he said. "I am not saying that somebody can't put together something less or less-engineered and have it work, but we chose to do it in that manner we feel confident with utilizing a substantial structure."

The CUPS structures, for the most part, cover between 10 and 15 acres each.

“We take the land, prepare that first, build the structures, put all the infrastructure and support structures in, and then the last thing you do is plant the trees into a clean environment,” he said. 

The growing method can produce fruit using substantially less fertilizer than an outdoor grove.

“When you can take and produce five times the amount of fruit per acre, that is a substantial savings from an environmental impact side of it," Callaham said. "You're using less land, you're using less water, you're using less fertilizer, less pesticides, to produce this crop.

“There’s a good story behind what we're doing,” he continued. “It's not just being able to survive in the Florida citrus industry, it is not just being able to produce high-quality, fresh fruit from the inside of the fruit to the outside appearance. It's a very, very environmentally friendly manner that we're doing that.”

With more than 200 grower members, the Dundee Citrus Growers Association is a grower-owned cooperative that was established in 1924. While citrus is the cooperative’s main business, the organization has diversified over the years and is now a harvester, packer and marketer for Florida peaches and blueberries. 

Callaham said Dundee's citrus growers also produce fruit in the traditional manner, using any technology available, to increase the productivity rate of trees, including using individual protective covers for trees. But for fresh fruit, Callaham said CUPS is going to be the group’s main focus moving forward to produce high-quality fruit.

In 1989, Callaham started working with the University of Florida citrus Research Center in Lake Alfred, so he has a connection to the place that led Dundee Citrus to pursue the CUPS growing method.

After his time at the Florida Citrus Research Center, Callaham continued his education, majoring in agriculture with an emphasis on citrus at the University of Florida. 

In 1995, he went to work for the Lake Wales Citrus Growers Association, which merged and joined the Dundee Citrus Growers Association in 1999. 

In 2003, Callaham was promoted to CEO of Dundee Citrus Growers Association.

Dundee Citrus primarily focuses on the U.S. and Canadian markets, but the firm also has a close relationship with Dan Richey and Riverfront Groves for export sales. 

Get closer

Seeing CUPS in person makes a big impact, Callaham said. 

Seeing pictures or watching a YouTube video is one thing, but the people who have been able to come out and visit CUPS citrus groves in person get a full grasp of the growing method.

“You walk inside one of these structures, you see how beautiful the trees are and how plentiful the fruit crop is on the trees, and how clean and nice it looks, and it is pretty amazing when you walk into a 10-acre structure, and it looks like you're standing in something that's 100 acres," he said. 

Buyers are anxious to be able to purchase grapefruit grown in the structures, and that won't be far away.

“We should have plenty to go around moving forward as our trees age and become more productive," Callaham said.

Inside CUPS facilities, citrus is planted at more than 300 trees per acre.

That is quite a bit higher than for a typical outdoor grove. Historically, citrus tree spacings in groves were 116 to about 145 trees to the acre.

Greening is the No. 1 problem for the Florida citrus industry, but the CUPS method does help with canker as well, he said.

“Canker is spread by wind-driven rain; the screen blocks the wind and keeps that wind-driven rain from driving that into the trees inside the structure," Callaham said. "So, it absolutely helps.”

The other way canker is spread is by equipment, and with CUPS, Dundee uses specific custom equipment that does not leave the CUPS site.

“It is only in our CUPS groves, we don't want to risk bringing in insects, bacteria or fungus, or anything from non-screen groves," he said. 

To get people and equipment in and out of the system, the CUPS facilities use a double-door system that is separated by a corridor.

“You open one set of doors, and you bring your sanitized equipment or personnel or whatever it is into there, and you shut one door," Callaham said. "And then, you're opening up this ... air lock-type system.”

Coming on

Callaham said more growers are looking at the CUPS technology.

“We are aware ... there's some other folks that are getting into it, and doing it in a small way, maybe more of a test type-size project,” he said. It isn’t easy or cheap to try to find a contractor to build a protected screen structure of 10 to 15 acres, however. 

“It’s not so easy to locate companies that have [built] these types of structures,” he said. “I think that it will expand in the future, but I think that there are some things that will keep that expansion slowed down to an extent."

Callaham said it is possible there may be 2,000 to 3,000 CUPS acres in five to 10 years. 

“Do I think it will be 10,000 or 20,000 acres? I really don't,” he said, noting that it takes a lot of capital to put the structures in place, combined with the practical limits on the manufacturing of screen facilities.

Callaham didn’t share what an investment in CUPS requires, but he said the outlays are determined by the topography of the land. The technology does provide some freeze protection, too.

“Instead of the frost settling on the trees, it'll settle in on the outside of the structure,” he said. The company will use its microjet irrigation system for freeze protection inside CUPS, just as growers would do in an outside grove.

Hurricanes are definitely a concern, but the Dundee CUPS units are well engineered, substantially built and rated to withstand hurricane force winds, Callaham said.

Callaham said Dundee Citrus has quite a few new mandarin plantings in traditional outside groves, in addition to some planted within the CUPS structures.

“It is something I think you are going to continue to see, of mandarins being planted in Florida," he said.

A genetically engineered solution, or any breeding solution, for citrus greening may not arrive in time.

“I think that practical solutions are going to be the quickest way to sustain the industry and sustain the volume and the quality. Long term, I think there will be some form of variety development,” he said, noting that he believes researchers may eventually find varieties that are more tolerant or resistant to citrus greening and citrus canker.

“We are in it for the long term, and we are here to stay," Callaham said. 

 

 

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