A Cure for Pierce’s Disease

By Chelsea McCall, Texas A&M AgriLife Research

A Texas A&M AgriLife Research study has led to the discovery of the first curative and preventive organic treatment against Xylella fastidiosa, the bacterium that causes the deadly Pierce’s disease in grapevines. It’s considered the world’s first.

The glassy-winged sharpshooter, the primary vector of Pierce’s disease, feeds on the sap of grapevines, spreading the disease vine-to-vine as it does. GLWSS is thought to be limited by cold winters, so in warm and arid places like Texas and California, Pierce’s disease spreads efficiently. But with temperatures rising from climate change, it’s feared that PD will spread more widely, more quickly. To date, most efforts to control Pierce’s disease have focused on the pest, often with deleterious effects on non-target beneficial insects such as honeybees.

This new solution is a bacteriophage therapy. Developed by Dr. Carlos Gonzalez, a professor in the Texas A&M College of Agriculture and Life Sciences Department of Plant Pathology and Microbiology and member of the Texas A&M AgriLife Center for Phage Technology, it is a precision treatment of bacterial infections that uses viruses to infect and kill the bacterium itself. In other words, this injectable treatment targets the disease within the plant’s vascular system, helping to cure the infected grapevine and stopping the spread to surrounding vines.

“Our research findings resulted in an injectable organic remedy that cures the plant from within rather than as a surface application.  As with any biological, if you rely on pesticides that are not systemic and it rains, it’s not going to do much good,” Dr. Gonzalez said. “Developing a bacteriophage treatment was ideal because it’s an organic remedy that works to cure the plant from within—rather than a pesticide that’s meant to kill insects that vector the pathogen.”

The bacteriophage therapy has been trialed in high-disease-pressure vineyards Northern California and, after two seasons, was reported to have reduced the incidence of Pierce’s disease by almost 60%.

Otsuka Pharmaceutical partnered with AgriLife Research in 2010 to develop a bacteriophage treatment for Pierce’s disease. Development was led by Dr. Gonzalez in collaboration with the company. The treatment has now been approved by the U.S. Environmental Protection Agency, EPA, with the commercial name XylPhi-PD, is registered for use in California, Arizona and Texas, and is approved for use in organic production by the Organic Materials Review Institute, OMRI. The product is now marketed in the U.S. by Otsuka subsidiary A&P Inphatec, LLC.

“The development of this first-ever bacteriophage treatment for Pierce’s disease is a significant step for the agricultural industry,” Dr. Gonzalez said. “Bacteriophage therapies will have a major impact on agricultural sustainability, as they’ll allow us to implement more ethical practices and growing techniques that are good for the plant and the environment.”


This article was adapted from the original, entitled Texas A&M AgriLife Research develops bacteriophage treatment for Pierce’s disease,” published May 28, 2021, on AgriLife Today, the online publication of Texas A&M AgriLife Research.

Elements of this article are included, as well: “World’s First Organic Treatment for Pierce’s Disease,” by Lee Allen, Western Farm Press, August 26, 2021.