FORT PIERCE — Citrus growers from several of Florida’s production regions joined researchers recently for a field day inside 14-foot high screenhouses that protect fruit trees from an invasive insect. The insect is the Asian citrus psyllid, which transmits the bacterium that causes the most serious citrus disease worldwide.

The outreach event, “CUPS (Citrus Under Protective Screens) Field Day,” took place at the University of Florida Institute of Food and Agricultural Sciences Indian River Research and Education Center (UF/IFAS-IRREC) in Fort Pierce. The host was Rhuanito “Johnny” Ferrarezi, assistant professor of citrus horticulture at IRREC. Co-hosting was Ferrarezi’s colleague, Jawwad Qureshi, assistant professor of entomology at the UF/IFAS Southwest Florida Research and Education Center in Immokalee.

“We conduct experiments inside the CUPS houses to investigate irrigation and fertilization management strategies and test different varieties to produce high-value citrus free of citrus greening, or Huanglongbing, or HLB,” said Ferrarezi. “We serve growers in Florida with research findings they can readily use in their operations.”

Qureshi and Ferrarezi’s team of 17 postdoctorate researchers, graduate students, visiting scholars, and research assistants greeted 25 guests, the maximum number permitted in the COVID-19-era. Participants included a citrus grower from South Georgia and Florida’s citrus industry members from Miami- Dade to St. Lucie, Indian River, Lake, and Highlands counties. Citrus production in southeastern Florida continues, despite a 90% drop from its 1990s heyday.

“The CUPS field day was a great learning event,” said Clay Lamar, from southwest Georgia. “Being a grower and nurseryman, I consider myself a forever citrus student, and there is nowhere better to learn than from Dr. Ferrarezi and his team.”

Lamar and other guests entered two of the four CUPS houses at IRREC to observe live experiments and operations. Each house is about 58,000 square feet, constructed with thick wooden utility poles supported by metal cables, and covered with a white 50-mesh screen. Inside CUPS, healthy citrus trees are 5 feet 5 inches by 10 feet apart. Irrigation emitters break through the sandy soil, and wide black strips of woven plastic ground cover block weeds and separate the rows of citrus trees. At the head of each citrus tree row are colorful signs that mark the different fruit varieties of grapefruit and mandarins. Each tree bears a zip-pull tag with its name typed neatly on the tag face.

“The screenhouses exclude the psyllid, but other insects can enter the houses,” said Qureshi. “Growers need to monitor and manage pests, beneficial insects, and mites found in the CUPS.”

Ferrarezi said Qureshi is a leading expert in monitoring and management of the Asian citrus psyllid and all of the insects found on citrus trees.

“The trees inside the houses are healthy and produce juicy, marketable fruit,” said Ferrarezi. “Our houses stand near the ocean and are susceptible to severe weather events. The growers could see that it is possible to produce fruit in the houses and protect the houses from hurricanes.”

The psyllid, citrus greening, and the threat of hurricane damage are some concerns growers have about production. Ferrarezi pointed out installation and ongoing maintenance costs as another factor he researches for the growers.

“Plastic mesh and other parts of the screenhouses are impacted by Florida’s severe weather and require regular replacement,” Ferrarezi said. “The IRREC CUPS houses are almost nine years old; the screening reached its lifespan and was replaced.”

Maintenance, operations, and crop protection are expenses citrus growers have always managed. Saving money on production and getting back into robust grapefruit production is an interest they all share. During the field day event, Ferrarezi explained how growers could conserve water with fertigation or a combination of irrigation with fertilizer mixed in the water. Ferrarezi also showed the visitors an automated irrigation controller and fertigation tanks.

“Water management can be highly efficient in CUPS systems,” said Ferrarezi. “And production data is strong too. We can plant trees in high-density configurations that produce much higher fruit yields, as highlighted in a scientific publication published in Frontiers in Plant Science in 2019 available at https://www.frontiersin.org/articles/10.3389/fpls.2019.01598/full.”