Photo courtesy of USDA-ARS
U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) geneticist Matt Mattia with the U.S. Horticultural Research Laboratory in Fort Pierce, Florida, recently provided a scion breeding update on HLB-tolerant citrus. A slightly edited version follows:
Significant strides are being made in the development and evaluation of new citrus varieties, with many now nearing commercial release. These varieties are not only promising in terms of fruit quality but also show improved resilience against HLB.
SWEET ORANGE-LIKE VARIETIES
One of the most exciting advancements this season is the near release of several sweet orange-like hybrids. These selections, including the standout FF-1-5-213, have undergone rigorous evaluation. They show superior juice quality with excellent Brix levels. Growers and processors have their eyes on these hybrids. However, there still remains a regulatory hurdle in using sweet orange-like hybrids in amounts greater than 10% in not-from-concentrate orange juice.
MANDARINS
Several seedless varieties of mandarins are showing excellent fruit quality and resistance to HLB. The seedless Page and Nova mandarins, now undergoing propagation trials, have been noted for their easy-to-peel characteristics and appealing taste.
GRAPEFRUIT
Re-selected grapefruit, considered a long shot, are also ready for trials. Selections like Florida Red, Henderson and Red Blush are under evaluation as single trees. These grapefruit selections, although not fully resistant to HLB, offer hope that with the right cultivation techniques, grapefruit could make a comeback in commercial production. The Florida Red, Red Blush and Henderson varieties in particular are being propagated for further trials, with potential to be more tolerant than commercially available options. In addition, several grapefruit-like hybrids are being evaluated for commercial fit.
INDUSTRY COLLABORATION ESSENTIAL
None of these advancements would be possible without the close collaboration between researchers, growers and processors. Large-scale processing trials with partners like the Coca-Cola Company have also been essential, helping identify orange-like varieties for juice production. These collaborations have led to the creation of an elite list of citrus varieties with high Brix levels and excellent flavor profiles.
The Citrus Research and Development Foundation, the Florida Department of Citrus and New Varieties Development and Management Corporation have funded this research.
VARIETIES AND OTC TREATMENTS
In addition to traditional breeding techniques, researchers are experimenting with treatments like oxytetracycline (OTC) injections to improve tree health and HLB tolerance. Early data suggests that different citrus varieties respond uniquely to OTC treatments, further informing breeding strategies that focus on improving tree tolerance.
HYBRIDIZATION EFFORTS
The 2024–25 season will also see the continuation of hybridization efforts, with thousands of new hybrids being evaluated for fruit quality and HLB resistance. These hybrids are the result of crossing materials from the oldest breeding collections, which can withstand Florida’s challenging growing conditions.
While the battle against HLB is far from over, these new selections represent a major step forward in ensuring the future viability of the state’s citrus industry.
Source: USDA-ARS
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