A treatment for citrus greening disease has received unconditional registration from the U.S. Environmental Protection Agency (EPA). The product, registered by Maryland-based Silvec Biologics Inc., has passed all regulatory reviews and is considered safe and effective for protecting citrus trees from huanglongbing, a disease that has significantly impacted the U.S. citrus industry.
The development follows more than a decade of research at Texas A&M AgriLife Research. Dr. Kranthi K. Mandadi, center director at the AgriLife Research and Extension Center at Weslaco and a professor in the Texas A&M University Department of Plant Pathology and Microbiology, led the scientific work.
His team demonstrated that naturally occurring antimicrobial peptides from spinach, known as defensins, can protect citrus trees from the disease.
According to Silvec, citrus growers are expected to gain access to the product in late 2026. The treatment relies on a nontransmissible strain of citrus tristeza virus (CTV) that is reprogrammed to prompt trees to produce the spinach-derived defensin peptide. Southern Gardens Citrus of Clewiston, Florida, noted that this technology does not alter the tree’s genome but functions similarly to an immunization.
A small piece of plant material from a specially developed source tree is grafted onto an existing citrus tree, where the CTV continues producing the defensin peptide to fight the disease bacteria.
The research effort began as a collaboration between Mandadi and Dr. Erik Mirkov, an AgriLife Research professor and plant pathologist in Weslaco. Early studies were supported by AgriLife Research, the Foundation for Food and Agricultural Research, and Southern Gardens Citrus.
