Skip to main content
Skip to main content
Give      University of Florida

UF/IFAS Indian River Research and Education Center (IRREC) Citrus Production and Other Tree Crops Research Laboratory 

UF/IFAS Indian River Research and Education Center (IRREC) Citrus Production and Other Tree Crops Research Laboratory 

The Millennium Block 

  • 2023 through 2024: A first fruit harvest for grapefruit was completed.  
  • 2022: Hurricane Ian crossed Florida, causing massive fruit drop in the Millennium Block. 
  • 2020: The first Millennium Block Drive-Thru event is held for growers to view the new varieties.  
  • 2019: The first new citrus varieties are planted in the Millennium Block.  
  • 2016: The Millennium Block was prepared for a new citrus research planting.  
  • 2005: Millennium Block grove “pushed” due to a plant pathogen ruling.  
  • 1999-2000: “The Millennium Block” name emerged for the first time to mark the 21st century.  
  • 1970s-through the 1999: Dr. David Calvert, a soil and water science professor for the UF/IFAS Indian River Field Laboratory, which became the UF/IFAS IRREC, initiated the Soil, Water, and Atmosphere Project. Otherwise known as “The SWAP Project,” the grove was the site of experiments to determine the impact of soils and water on citrus trees and included studies about pathogens. The SWAP Project became the Millennium Block just before 2000.  

Dr. Zambon leads the research at the “Millennium Block”, an active 20-acre citrus research grove that features more than 5,500 trees developed by UF/IFAS and USDA plant breeders.  

The objective of the “Millennium Block” is to identify new citrus varieties that will tolerate citrus greening, the world’s most serious citrus disease. Also known by huanglongbing, or simply, HLB, the disease was first discovered in China, and it means “the yellow dragon disease”. HLB is caused by a bacterium named Candidatus Liberibacter asiaticus, vectored by the Asian Citrus Psyllid, and it is the main cause of the citrus decline over the last 20 years. Grapefruit is the prize crop for Indian River District growers. Exported to points as far away as Korea and Japan, pink and red grapefruit is known to be the world’s finest fresh grapefruit. 

 

The “Millennium Block” includes grapefruit, mandarin and sweet orange, and several rootstock varieties, divided into two distinct objectives: 1) identification of HLB tolerance in various grapefruit/rootstock combinations (Trial 1); 2) performance of developed rootstocks, a grapefruit, a sweet orange, and a mandarin scion, towards abiotic and biotic stress tolerance (Trials 2, 3 and 4). 

The trials are described below: 

  • Trial 1: 18 grapefruit scions and 3 rootstocks, totalizing 54 combinations.  
  • Trial 2: 32 rootstocks grafted with 'Ray Ruby’ grapefruit. 
  • Trial 3: 32 rootstocks grafted with ‘Glenn Navel’ sweet orange. 
  • Trial 4: 32 rootstocks grafted with ‘UF-950 Mandarin’. 

Each year ahead of harvest season, the Horticulture Production Lab hosts “The Millennium Block Drive-Thru" event to showcase the citrus varieties. The event is open to the public and offers an opportunity to interested researchers, growers, industry leaders and the public, to see the trials and engage with the researchers that are part of the project.  

 

The "Millennium Block” is funded by the Florida Department of Citrus (FDOC). 

Maintenance for The Millennium Block is funded in part with interest gained on the John T. Moose IRREC Enhancement Endowment. 

 

The Millennium Block is entering its sixth year of study. After seven years of data collection and study, Dr. Zambon will release results the university feels will deliver reliable data upon which growers to make production decisions. 

Some varieties show early tolerance to citrus greening, or HLB. But it is necessary to observe the fruit and collect data for seven years. The most revealing observations at this time are that pummelos, or grapefruit-like varieties, show early tolerance to disease. 

"UF 914" is a UF-bred grapefruit-like pummelo developed by UF/IFAS citrus breeder Dr. Fred Gmitter. The variety shows subtle citrus greening response. But, overall, the fruit is healthier than other varieties in their response to endemic citrus greening.