CUPS Trees Survive Freeze Nearly Unscathed

During a Feb. 26 Highlands County ag tour hosted by University of Florida Institute of Food and Agricultural Sciences Extension, participants had the opportunity to go inside a citrus under protective screen (CUPS) pod.

Bill Bohde, director of agronomy for Dundee Citrus Growers Association, led the tour group through a 10-acre CUPS pod at Fort Meade in neighboring Polk County. The screened structure is the growing environment for Ray Ruby grapefruit on US-897 rootstock planted at 324 trees per acre. The Fort Meade farm includes a total of 500 acres of CUPS-grown grapefruit.

While CUPS are well known for protecting trees from the Asian citrus psyllid, they proved to have additional protective powers during the late January/early February freeze. According to Bohde, the screens helped reduce windspeeds during the three-night freeze event. He said temperatures were the same inside and outside of the CUPS. However, wind gusts outside the CUPS measured up to 30 mph but were only 7 mph in the CUPS. The reduced wind, along with microjet irrigation, helped prevent damage.

“We lost a little flush, but it is already growing back,” said Bohde. “Some early bloom was destroyed, but there was zero tree or fruit loss and no ice in fruit.”

Bohde said that while traditional groves in Florida are currently averaging 75 boxes per acre, his mature CUPS trees are yielding 700 to 800 boxes per acre. He packs 97% of the crop for the fresh market, sold under the Rubies brand.

Bohde shared additional information and observations on his CUPS production:

• Trees grow three times faster in CUPS.
• Not one screen panel was lost to Hurricane Milton, even though the eye of the storm was only 1 mile away.
• The screens, which are imported from Spain, have a 7-year expected lifespan. Weather degrades them, and hurricanes cut that life expectancy in half.
• The harvest season runs from late September to April 1. The later picks have higher Brix but less shelf life.
• Acid is lower in CUPS-grown grapefruit, giving it a milder taste.
• Herbicides are only applied once per year.
• Soil moisture sensors are used.
• Chilli thrips are currently a problem.
• Only tree middles are pruned. Hedging is done when trees are three to four years old. Trees have not required topping.