Xylella Fastidiosa

Xylella fastidiosa is a bacterial pathogen responsible for a wide range of plant diseases. It has made its way into Oklahoma, and that’s something local growers and researchers are taking very seriously. Diseases like Pierce’s Disease in grapes and bacterial leaf scorch in shade trees are linked to this bacterium. Over the last two decades, research in Oklahoma has revealed the growing footprint of this plant killer, and with rising temperatures, the risk is likely to go up.

This post gives you everything you need to know about Xylella fastidiosa in Oklahoma, based on five important studies. From proof of its presence to its economic impact and management strategies, this blog breaks it down in clear, simple terms.

 

 

Xylella fastidiosa (XF) is a bacterial pathogen that blocks the water-conducting tissues (xylem) in plants. This causes a variety of symptoms including leaf scorch, yellowing, stunted growth, and plant death. It's transmitted mainly through insect vectors like sharpshooters and spittlebugs. Once infected, the plant struggles to get water and nutrients, leading to visible stress and damage.

This bacterium causes several diseases, such as:

·         Pierce’s Disease in grapevines

·         Bacterial Leaf Scorch (BLS) in trees like elm, oak, and sycamore

·         Phony Peach Disease in peaches

 

Proof of Presence in Oklahoma

Study 1: Pierce’s Disease in Canadian County

In 2008, Oklahoma grapevines showed signs of Pierce’s Disease for the first time. The infected plants were found in Canadian County, displaying symptoms like leaf yellowing and browning edges. Oklahoma State University researchers ran tests and confirmed Xylella fastidiosa was the culprit. They used real-time PCR and serological (ELISA) tests to confirm the infection.

·         Reference: Smith, D. L., Dominiak-Olson, J., & Sharber, C. D. (2009). Plant Disease, 93(7), 762

Study 2: First Detection in Elm Trees (2004)

Before grapevines, XF was first detected in 2004 in elm trees at the Oklahoma Botanical Gardens in Stillwater. Researchers found the bacterium in a symptomatic elm through PCR testing and DNA sequencing.

·         Reference: Olson, B. R. et al. (2006). Plant Disease, 90(1), 108

Your provided summary confirms: "XF was first detected in elm trees in 2004 and later in grapevines in 2008, marking a confirmed spread in plant hosts across Oklahoma."

 

 

Spread Across Oklahoma

Study 3: Statewide Surveys in 2016-2017

By 2016-2017, Xylella fastidiosa had been found in multiple counties including Atoka, McCurtain, Cleveland, and even a reappearance in Oklahoma County. Surveys showed this wasn’t just a local issue—it was becoming a statewide concern.

·         Sharpshooter insects (like Graphocephala versuta) were identified as major carriers.

·         PCR and ELISA confirmed XF presence in infected vines.

·         Reference: Wallace, Sara Elizabeth. (2018). Detection and Diagnosis of Red Leaf Diseases of Grapes in Oklahoma. Master’s thesis, Oklahoma State University.

Study 4: Insect Vectors and Weedy Hosts

The 2013 study by Lisa M. Overall found that insect vectors and certain plants in vineyards could harbor XF. Sharpshooters like G. versuta and glassy-winged sharpshooters were confirmed as carriers. 2.4% of insects tested were positive.

·         Reference: Overall, L. M. (2013). Doctoral dissertation, Oklahoma State University.

Study 5: Seasonal Insect Spread and Natural Transmission

From 2008 to 2010, researchers confirmed that the insects found in Oklahoma vineyards were not only infected but capable of transmitting XF to healthy plants like ragweed and alfalfa. G. versuta showed the highest infectivity.

·         Reference: Overall, L. M., & Rebek, E. J. (2015). Journal of Economic Entomology

 

 

Summary Table: Spread and Impact in Oklahoma

Study	Year	Location	Host Plant(s)	Insect Vectors	Confirmed XF	Notes
Study 1	2008	Canadian County	Grapevine	N/A	Yes	First grapevine case (Pierce’s Disease)
Study 2	2004	Stillwater	Elm tree	N/A	Yes	First confirmed case in Oklahoma
Study 3	2016–2017	Atoka, McCurtain, Cleveland, OK County	Grapevines	G. versuta, H. vitripennis	Yes	Statewide survey confirmed spread
Study 4	2010–2013	Vineyards and nurseries	Grape, weeds, trees	G. versuta, C. costalis	Yes	Identified insect carriers and plant reservoirs
Study 5	2008–2010	Central OK	Alfalfa, Ragweed	G. versuta, O. orbona	Yes	Confirmed natural transmission

 

Impact on Oklahoma Agriculture

XF’s spread threatens local agriculture in several ways:

·         Grapevines: Oklahoma’s wine industry is still growing, but XF can destroy entire vineyards.

·         Shade Trees: Elms, oaks, and sycamores—used widely in urban landscaping—are vulnerable.

·         Economic Costs: Infected plants must be removed and replaced, and the cost of managing vector insects adds to the burden.

As the climate warms, insect vectors could expand their territory, further increasing the risk.

 

Managing the Spread

What Can Be Done?

·         Insect Control: Monitor and reduce sharpshooter populations during summer.

·         Clean Equipment: Pruning tools can spread the bacteria. Clean them often.

·         Remove Infected Plants: Rogue out visibly infected vines or trees.

·         Resistant Varieties: Some grapes like 'Black Spanish' show better resistance to XF.

·         Monitor and Report: Stay informed and report symptoms to local extension services.

 

Final Thoughts

Xylella fastidiosa is already in Oklahoma and spreading. With multiple studies proving its presence in grapevines, shade trees, and even insect vectors, growers and land managers must stay alert. The good news is, we have the knowledge, research, and tools to fight back. But it starts with awareness and smart action.

 

References

·         Olson, B. R., Dominiak, J., von Broembsen, S., Berg, M., and Bextine, B. R. "First Report of Xylella fastidiosa in Oklahoma." Plant Disease 90, no. 1 (2006): 108. https://doi.org/10.1094/PD-90-0108B.

·         Smith, D. L., Dominiak-Olson, J., and Sharber, C. D. "First Report of Pierce's Disease of Grape Caused by Xylella fastidiosa in Oklahoma." Plant Disease 93, no. 7 (2009): 762. https://doi.org/10.1094/PDIS-93-7-0762B.

·         Wallace, Sara Elizabeth. Detection and Diagnosis of Red Leaf Diseases of Grapes (Vitis spp) in Oklahoma. Master’s thesis, Oklahoma State University, 2018.

·         Overall, Lisa Marie. Incidence of Xylella fastidiosa in Oklahoma, a Survey of Potential Insect Vectors, and Identification of Potential Plant Reservoir Hosts. Doctoral dissertation, Oklahoma State University, 2013.

·         Overall, L. M., and Rebek, E. J. "Seasonal Abundance and Natural Inoculativity of Insect Vectors of Xylella fastidiosa in Oklahoma Tree Nurseries and Vineyards." Journal of Economic Entomology (2015): 1-10. https://doi.org/10.1093/jee/tov261.