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UF/IFAS image by drone by Martin Zepien

UF/IFAS Millennium Block citrus grove drive through event

Curbside grocery pick-ups and high school drive-through graduations are the new normal, and so too are University of Florida citrus research grove visits.

Rhuanito “Johnny” Ferrarezi will host what will likely be the first drive-through citrus grove field day – a view of a large-scale research trial — for growers and other citrus industry stakeholders. The event, the IRREC Millennium Block Variety Trial, will be held on Oct. 9, from 9:30 a.m. until noon, at the University of Florida’s Institute of Food and Agricultural Science’s Indian River Research and Education Center (UF/IFAS-IRREC). The street address for the Millennium Block is 7850 Pruitt Research Road, Fort Pierce, Florida, located within a couple of miles from both Interstate 95 and Florida Turnpike Fort Pierce exits.

Those interested may register at the following online link: https://www.eventbrite.com/e/ufifas-irrec-millennium-block-drive-thru-field-day-tickets-122165491273.

“We recommend visitors drive their personal or company-owned pick-up trucks or other off-road vehicles and remain on designated areas within the grove,” said Ferrarezi. “Swales are present next to canals, and the grove is an active research site.”

Ferrarezi is an assistant professor of citrus horticulture at IRREC; his research involves experiments, or trials, to help citrus producers continue to grow Florida’s signature fresh fruit crop and all of its varieties. The Millennium Block is a 58-acre field in which more than 4,400 1-year-old and 1,100 recently planted healthy trees grow. Ferrarezi said he and his laboratory associates will plant about 700 more trees next spring.

“We have a grapefruit scion trial with 18 selections on three commercial rootstocks, and three independent rootstock trials with ‘Ray Ruby’ grapefruit, ‘Glenn 56-11’ navel orange and ‘UF 950’ mandarin as scions,” said Ferrarezi.

Field day attendees will stop at tented information booths positioned at the trial entrance. Researchers, graduate students, and members of the Ferrarezi Lab Team, along with Extension professionals, will respond to questions and provide printed maps and key plant growth data for each citrus variety under study.

“At each research plot, visitors can stop, look at each group of trees, and visually identify those they feel are the best performers,” Ferrarezi said.

Each experimental unit is comprised of five trees identified by a code tag and is replicated six times across the trial. Participants who wish to take an electronic survey will have an opportunity to demonstrate their previous knowledge of the Millennium Block varieties and report their learning experience during the field day tour.

“The event is an opportunity for citrus growers, farm managers, crop advisors, industry partners, researchers, students, and faculty to see the early stage of a large-scale citrus tree field trial,” said Ferrarezi. “The Millennium Block is a trial to determine which scion and rootstock combinations can better adapt to the Indian River’s Flatwoods soils and tolerate citrus canker and citrus greening while producing profitable crops.

In the Indian River District, citrus greening disease (Huanglongbing HLB) has reduced citrus grapefruit production by 90%. An invasive insect, the Asian citrus psyllid, carries the bacterium that causes the disease from infected trees to healthy trees. The disease presents itself in citrus trees as leaves change from deep to lighter shades of green. Infected trees drastically reduce yield, but with best practices developed by UF/IFAS scientists, growers can sustain trees for many more years.

“One of the best strategies to keep citrus groves productive in current HLB times is fruit variety improvement,” said Ferrarezi.

Ferrarezi said UF/IFAS plant breeders Jude Grosser, Fred Gmitter, and Bill Castle, at the UF/IFAS Citrus Research and Education Center in Lake Alfred, developed citrus varieties they expect will tolerate HLB. Geneticists Ed Stover and Kim Bowman with the U.S. Department of Agriculture Horticultural Research Laboratory in Ft. Pierce (USHRL) also contributed citrus varieties for the study.

“We are testing the best-released grapefruit scions and rootstocks available,” Ferrarezi said.

Bill Castle, UF Emeritus Professor, and Peter Spyke, a local grower, actively guided citrus variety selection for the project, along with Indian River Citrus League board members and the USHRL director and researchers.

Ferrarezi said the field trials are a cost-effective method to test rootstock-scion or a combination of roots grafted with trees. Ferrarezi expects many of the trees will succumb to HLB, but the idea is to identify a combination that can adapt well to the Indian River soil type, climate, and unique pest and disease pressure.

“Some of the citrus tree varieties will survive, but others will thrive,” said Ferrarezi. “Those trees will generate strong data to guide science-based decisions and bring growers back to business.”

Ferrarezi said the IRREC Millennium Block variety performance trial has two major scientific objectives:

To assess new grapefruit scion cultivars’ performance with three commercial rootstocks under HLB endemic conditions in the Indian River district.

To compare grapefruit, navel, and mandarin growth and yield in the Indian River among trees on standard rootstocks, UF Rootstocks, and other recently released rootstocks.

The Millennium Block study is funded by the Citrus Research and Development Foundation grant 18-037C and IRREC Director, Ronald Cave. Early funding was provided in 2017 by then UF/IFAS Dean of Research Jackie Burns.

“The project is looking so remarkable due to the technical contributions of Ferrarezi Citrus Horticulture Laboratory and IRREC staff members Tom James, Randy Burton, Liz Calise, and Beth Curry,” said Ferrarezi. “I would also like to recognize my graduate student, Jose Martin Zapien Macias, and Thomas Stopyra, a longtime local citrus producer, for their contributions to the research.”

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