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.
