Citrus Commission Learns About HLB-Tolerant Trees, Other Research

Jim Rogers Florida Department of Citrus, HLB Management, Research

At the Florida Citrus Commission meeting earlier this month, a federal scientist outlined an eight-step action plan for research and development of heirloom orange trees that appear to be tolerant to HLB. Brian Scully, director of the U.S. Department of Agriculture’s (USDA) Horticultural Research Laboratory, discussed the Donaldson and Tobias trees at USDA’s Whitmore Foundation Farm. A third tree is also being investigated from the same location; it’s called the St. Michael tree.

Scully said rapid scion multiplication via tissue culture and other methods is being explored. The fruit from the trees has been processed and pasteurized. More work is needed before determining whether the trees are viable options for growers, and expectations must be managed, Scully said.

Citrus commissioners also heard about other ongoing research from the Citrus Research and Field Trial (CRAFT) Foundation and the New Varieties Development and Management Corporation (NVDMC).

HLB Research
The Donaldson tree at the Whitmore Foundation Farm is producing well despite HLB infection.

Tamara Wood, CRAFT Foundation program manager, provided an update on the organization’s progress. She said the first round of projects in Cycle 1 are all in the ground with one full year of production complete. Data is currently being collected and analyzed.

Cycle 2 has more than half of the planned trees planted, but widespread tree-delivery delays have led to extensions for some. Cycle 3 is under development with applications being evaluated and trees expected to be in the ground by December 2022. Funding for Cycle 4 is still being sought, with some money expected from the state.


NVDMC Executive Director Peter Chaires provided updates on several University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) projects.

A UF/IFAS Gainesville project is focused on breeding disease-resistant citrus cultivars. A total of 15 selections were made during the 2021 season, including seven sweet orange-like and/or tangor selections, four grapefruit-like selections, three mandarin selections and one lemon-like selection. The most promising are juicing tangor Fla. 21-10, grapefruit Fla. 21-07 and mandarin Fla. 21-05.

A UF/IFAS postharvest project is determining the ability of fruit from promising new citrus selections to maintain excellent quality through harvest and postharvest handling. So far in 2021–22, 14 selections are being evaluated with more anticipated.

A UF/IFAS Citrus Research and Education Center (CREC) project has identified one late-maturing (February) sweet-orange-like hybrid, with deep juice color, good ratio and Brix higher than14. The CREC project has also identified several new grapefruit types exhibiting better HLB tolerance thus far than standard grapefruit, and with superior fruit qualities. Additionally, the project has identified two early mandarin selections with excellent appearance, color, flavor, peel-ability, seedlessness and overall eating quality.

Source: Florida Department of Citrus

HLB Research

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