Florida farmers have observed, almost powerless, the spread of the huanglongbing bacterium (“yellow dragon disease” in Chinese), known worldwide as “HLB” and native to China. It was first reported in Florida in 2005, and has been conquering groves ever since.
The bacterium causes one of the most devastating citrus diseases called “greening”: the leaves of the infected trees turn pale, the fruit fails to ripen and remain green, and eventually fall to the ground.
The bacterium is transmitted by a small insect called citrus psyllid.
Compared to the 2003-2004 season, Florida’s orange production will be down by 80 percent this season (harvests last from November to April depending on the citrus variety). Grapefruits are the most affected.
Florida citrus farmers have generally been reluctant to destroy contaminated trees, and as a result 90 percent of their groves are infected—compared to only 19 percent in Brazil, while Europe so far has been spared the blight. Sprays used to treat trees in Florida have been ineffective.
Of 7,000 citrus growers in the state in 2004, 5,000 have thrown in the towel, according to The Washington Post.
Spyke is taking a long-term approach to the problem by searching for citrus varieties that are naturally more resistant to HLB. On his 30-acre farm he has planted two dozen varieties of citrus including lemons, oranges, mandarins and grapefruit.
The 68-year-old farmer knows it will take years, but is resigned to the idea that there is no miracle solution. He has also changed the way he looks after the trees.
“We have to use appropriate cultural practices that will help it deal with the disease,” he told AFP.
One solution is to feed the plants “slow release” fertilizer, so that the nutrient supply is regular and continuous.
This apparently helps some trees fight against the effects of HLB, which literally “starves” them to death.