In the search for ways to survive citrus greening, some growers have chosen the citrus under protective screen (CUPS) system as their solution. While CUPS can be costly to construct, it has proven to effectively prevent the deadly disease. But some have asked if the structures would hold up in extreme weather and adequately protect the trees. Hurricane Ian helped answer that question.
The Dundee Citrus Growers Association (DCGA) performs caretaking and harvesting for the largest CUPS project in Florida. Located east of Bartow, the Dundee CUPS is approximately 450 acres.
SOME SCREENHOUSE DAMAGE
Steven Callaham, DCGA chief executive officer, said the Dundee CUPS weathered Ian extremely well. “We were very fortunate,” said Callaham just days after the storm. “The structures performed exactly as they were engineered to. We had no structural damage, just some torn screens and broken cables. Repairs began immediately after the storm passed, and within a couple of weeks, you won’t even know a hurricane came through.”
Arnold Schumann, University of Florida Institute of Food and Agricultural Sciences professor, reported moderate damage to the 1.33-acre CUPS at the Citrus Research and Education Center (CREC) in Lake Alfred. He said there was one large tear in the roof panel seam, three broken steel anchor cables, loosened cables and loose or leaning wooden support poles.
“Partial detachment of the screen from adjacent buildings and doors caused small openings,” said Schumann. “We were able to patch the major breaches in the screen within a couple of days. The realignment and setting of poles and cables will take longer.”
Schumann noted that after the screenhouse was sealed, a broad-spectrum insecticide was sprayed on the trees in the CUPS to eliminate Asian citrus psyllids that may have established themselves while the roof was partially open. The psyllids are the vector for citrus greening.
TREES STAND TALL AND HOLD FRUIT
While Ian’s damage to the CUPS structures was minimal to moderate, the trees inside the CUPS help up very well. “The trees look great,” reported Callaham. “We have seen a considerable amount of fruit drop in the groves near our CUPS site; however, we did not have any within our CUPS.” He also noted there were no downed trees in the Dundee CUPS and this year’s CUPS harvest will not be impacted in any way by the hurricane.
Schumann had similar good news to share for trees in the CREC CUPS: “The trees in the CUPS were undamaged, and fruit drop was negligible, estimated at less than 0.5%,” he said. “The only fruit drop occurred where moving poles shook the trees in contact with them. Trees outside the CUPS had considerable fruit drop and some branch damage.”
RAIN AND WIND
Flooding was the source of much damage in some open-field groves but was fortunately not a concern for the Dundee and CREC CUPS.
“Flooding can be a factor with CUPS, as it can with any grove, so site selection is very important,” said Callaham. “Our projects are located at high elevations with well-drained soils. We had over 19 inches of rain and did not experience any flooding.”
“Rainfall of 8.9 inches was recorded at the CREC during the hurricane event and caused brief flooding only during the storm peak,” said Schumann.
According to the Florida Automated Weather Network, Hurricane Ian produced 13.5 hours of tropical storm force wind gusts (>39 mph; maximum 51.5 mph) at the CREC CUPS.
Stronger winds blew through the Dundee CUPS. In Bartow, the highest wind gusts recorded by the National Weather Service were 76 mph.
“Hurricane Ian was a true test for CUPS, and the outcome validates our model,” said Callaham.
He is pleased to report that the hurricane did not deter DCGA’s plan to double its CUPS acreage in southern Polk County, just east of Fort Meade. “We are moving forward, without delay, on our expansion project,” concluded Callaham. The project includes 500 acres of CUPS.
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