After 15 Years of Research, Spinach Just Helped Save American Citrus.
After 15 years of collaborative research, Texas A&M AgriLife scientists have
developed a citrus greening treatment—derived from antimicrobial peptides
found in spinach—that just received full EPA registration and is headed to
Florida groves by the end of the year.
By Texas A&M AgriLife Research — summarized for agInnovation
Citrus greening (known scientifically as Huanglongbing, or HLB) is one of the most destructive plant diseases in modern agriculture. It spreads through an insect vector, has no cure, and causes infected trees to produce bitter, misshapen fruit that falls prematurely from the branch. Growers can’t harvest it, can’t sell it. Florida’s orange groves, once the backbone of the state’s agricultural economy, have taken devastating losses since HLB arrived, and the U.S. citrus industry has struggled without a reliable treatment for decades.
The answer, it turns out, may have been hiding in spinach. Researchers at the Texas
A&M AgriLife Research and Extension Center in Weslaco, led by Dr. Kranthi Mandadi,
discovered that spinach naturally produces antimicrobial peptides called defensins and that those peptides can protect citrus trees from the bacteria associated with HLB. Fifteen years of collaborative research followed, involving partners at the University of Florida and the Citrus Research and Education Center, as well as Southern Gardens Citrus (a subsidiary of U.S. Sugar) which championed the technology through sponsored research and development. The delivery solution is elegantly indirect: a naturally non- transmissible strain of citrus tristeza virus—a benign virus already common in Florida citrus trees—was reprogrammed to continuously produce the spinach defensin peptide from within the tree. Growers simply graft a small piece of a specially developed source tree onto their existing trees. The tree’s own genome is never altered. It functions like an immunization.
In August 2026, the U.S. Environmental Protection Agency granted unconditional
registration to the treatment, clearing it for commercial sale and use nationwide, with no tolerance limit on residues. Maryland-based Silvec Biologics holds the commercial registration, with patent rights to the defensin technology held by the Texas A&M University System and the CTV delivery technology by the University of Florida. Florida growers are expected to begin gaining access through Silvec’s Florida CRAFT (Citrus Research and Field Trial) program in late 2026. The research team is already looking beyond citrus, exploring whether spinach defensins can protect potato crops from zebra chip disease and investigating new peptide combinations for broader crop protection.
This is what long-term public investment in agricultural science looks like. The research was supported over 15 years by AgriLife Research, the Foundation for Food and Agricultural Research, Southern Gardens Citrus, and multi-state coordinated
agricultural projects funded through the USDA National Institute of Food and
Agriculture’s Emergency Citrus Disease Research and Extension Program. Without that sustained, multi-institutional commitment, the funding gaps that kill most promising research would have ended this one too. American citrus growers, and American consumers, are the beneficiaries.
Read the full story at Texas A&M AgriLife Today for more on how the treatment works and what comes next.
Read the full story: Spinach Peptide Discovery Leads to Citrus Greening Treatment
Work like this—patient, sustained, and built on public trust in agricultural science—is
exactly what agInnovation exists to highlight. Share this story and subscribe to our
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