By Manjul Dutt, Sheetal Ramekar and Gary England

The grapefruit was created by chance from a cross between a pummelo and a sweet orange. It was first discovered in Barbados in the 18th century.

All the commercially sold grapefruits today trace their roots back to the Duncan variety of grapefruit. Cultivars existing today were developed through natural and induced mutations as well as seedling selections. As a result, all grapefruits are very similar to one another, differing mostly in small variations in their DNA.

A recent study on a newly discovered bud sport of the Flame grapefruit, found in Bill Lennon's citrus grove in Lake County, Florida, has highlighted how natural variations can offer hope in the fight against HLB. This bud sport displayed several improved qualities. These include darker leaves, better canopy density and improved HLB tolerance compared to the Flame grapefruit from which it was derived.

Preliminary data seems to indicate that this bud sport is later maturing than regular Flame, and fruits reach maturity in early January under endemic HLB conditions (Figure 1).

Biochemical tests revealed higher chlorophyll content and lower starch accumulation, suggesting that the bud sport manages resources more efficiently under HLB stress.

Certified budwood of this new selection is freely available from the Florida Department of Agriculture and Consumer Services Division of Plant Industry's Citrus Budwood Program for nurseries and growers interested in producing it.

Manjul Dutt is an assistant professor, and Sheetal Ramekar is a postdoctoral research associate — both at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center in Lake Alfred. Gary England is a UF/IFAS emeritus Extension agent.

HLB Deformed Citrus