Citrus greening has devastated Florida’s orange industry. Researchers and pioneering farmers now see cover crops as a possible road to recovery.
For the last couple of decades, a tiny insect called the Asian citrus psyllid has fed on the stems and leaves of the orange trees in Florida, infecting them with bacteria that cause a lethal disease called citrus greening. The bacterial disease, huanglongbing (HLB), originated in China and has destroyed 90 percent of the state’s groves, devastating its $9 billion citrus industry.
After years of seeking remedies (everything from antibiotics to GMOs to psyllid-sniffing dogs) with little success, Florida’s embattled citrus growers have discovered a new tool, thanks to the work of researchers at the University of Florida: planting cover crops amidst the orange groves. These crops, which can include legumes, brassicas, or clovers, are not grown for commerce, but instead to improve soil by adding nutrients, helping with water retention, deterring weeds and certain pests, and often attracting beneficial insects.
In the case of Florida citrus, greening affects the soil microbial community and nutrient uptake, decreasing many soil microbes important for the nitrogen cycling necessary for plants’ survival. When the psyllid attacks the trees’ roots, they can no longer absorb the water and nutrients the trees need to thrive.
Juanita Popenoe, agricultural extension agent for commercial fruit production at the University of Florida Institute of Food and Agriculture Science (UF/IFAS), is working with a few Florida growers who are using cover crops to combat citrus greening. She and her colleagues at UF/IFAS are cautiously optimistic.
“Cover crops show remarkable promise,” Popenoe says. “Right now, there’s not enough data available to recommend [cover crops] as a viable remedy for citrus greening, but it looks good.” If trees are healthy, they can still produce good fruit even if they have HLB, she added.