On an idyllic orange grove in Florida, trouble is brewing.  The Asian citrus psyllid, a brown and white mottled bug, creeps across a green leaf on an orange tree, transmitting a bacterium called Candidatus Liberibacter asiaticus onto the plant, causing a disease called citrus greening. Once infected, there is no cure. Since the disease’s spread across the state beginning around 2008, this horticultural horror has played out everywhere from massive commercial farms to grandma’s prized backyard oasis, threatening growers’ livelihoods and Floridians' sense of self.  

When the Spanish introduced it to the Americas in the 1490s, no one could have predicted that the humble orange would become synonymous with the state of Florida. “Citrus is part of Florida’s identity,” says Alyssa Vinson, the residential horticultural agent at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Extension in Manatee County. “If you go back to the original postcards and advertisements to tourists, images of oranges are everywhere.” From glossy print ads of rosy-cheeked children getting their daily cup of vitamin C or frolicking beachgoers enveloped in a wreath of blossoming oranges, the fruit represents a slice of Americana. “Having a citrus tree in your yard is the iconic Florida dream,” adds Fred Gmitter, a professor of citrus breeding and genetics at the University of Florida. 

“Citrus greening smacked the industry hard starting in 2008. Going into 2015, we started to see a mass spread of the disease, which damages the vascular tissue of the plant so that it can’t transport nutrition throughout the tree,” says Vinson. “We told people not to plant citrus anymore. Citrus greening takes away something meaningful to people because they have many emotions and memories wrapped up in growing citrus at home. All the time, we heard people say ‘I wish I still had my tree.’” 

As the detrimental disease marched its way across the state, Gmitter and his team at the UF/IFAS Citrus Research and Education Center in Lake Alfred released the Sugar Belle, a cross between a Clementine mandarin and a Minneola tangelo, known as the Honeybell. “It was the worst possible time to release a new citrus variety,” he adds, “and no one wanted to plant it.” One grower on the east coast of Florida—who, as luck would have it, learned about the fruit at a Gator football game—planted around 100 acres of Sugar Belles and was the only grower to do so. About a year or two after planting the trees, he asked Gmitter to come look at them, as they all displayed symptoms of greening on their leaves. Since he’d invested a great deal of money into the trees, the grower decided to leave them in the ground and see what would happen. “That was a stroke of luck because we discovered that the Sugar Belle is one of the most tolerant trees to citrus greening disease,” Gmitter says. “They continued to grow despite being infected and for many years continued to produce good crops of high-quality fruit.”

The Sugar Belle’s tolerance of citrus greening has encouraged the UF/IFAS to recommend it to home growers and test it for juicing. “It’s not resistant, but we feel that if they put in the work and give it proper nutrition,  home gardeners have a fighting chance to have a tree in their yard,” he adds. While the Sugar Belle isn’t a permanent solution for citrus greening, researchers use it as a breeding parent, transmitting tolerance of the disease to the next generations of trees through the simple transfer of pollen from one flower to another, producing plants that are not genetically modified. “We collect the seeds, grow out the babies and pick the one out of 1,000 that’s better than the others,” he says. 

Harkening back to naturalist Gregor Mendel’s work breeding peas in the 1800s, this old-fashioned scientific process represents a return to a life lived in harmony with nature. Scientists and volunteers work with UF/IFAS to gather data on the trees, helping home and commercial growers. “We live in a culture that’s disconnected from the natural world,” adds Vinson, “so any opportunity for us to give people autonomy over their food choices is important. Connecting people with the plants around them can provide a sense of place and a healthier ecosystem.”