Xylella Fastidiosa

Xylella fastidiosa, a harmful bacterium, has become a serious threat to U.S. agriculture in recent years. Affecting crops like grapevines, citrus trees, almonds, and olives, its impact is felt in farming regions across the country. The bacterium disrupts water flow in plants, causing diseases such as Pierce’s disease in grapevines, bacterial leaf scorch in hardwood trees, and citrus variegated chlorosis. Spread by insects like sharpshooters and spittlebugs, Xylella fastidiosa infects plants' vascular systems, leading to water stress, wilting, and plant death. The pathogen has already caused significant crop losses, especially in states where it is most prevalent. It’s not just limited to commercial crops; ornamental plants and trees in urban areas are also at risk. With its spread across over 40 states, scientists are working to track and control Xylella fastidiosa. In the following sections, we'll delve into the specific challenges faced by each state and the ongoing efforts to manage this destructive pathogen.

Alabama

Xylella fastidiosa, a bacterial pathogen, is rapidly spreading in Alabama, threatening crops like blueberries, grapes, peaches, and plums. Transmitted by sharpshooter insects, it causes bacterial leaf scorch and Pierce's disease, leading to stunted growth and reduced fruit yields (Ma, 2010). Auburn University research highlights blueberries' susceptibility to bacterial leaf scorch and suggests disease-resistant cultivars (Potter, 2010). Sharpshooters, abundant in Alabama's Gulf Coast, are key vectors for Xylella (Ma et al., 2010). The spread has caused significant damage to muscadine grapes and blueberries (Ma, 2010). Integrated pest management, including vector control and resistant crops, is vital for protecting Alabama's agricultural economy. 

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Arizona

Xylella fastidiosa is confirmed in Arizona’s agriculture, particularly in pecan orchards, Chitalpa tashkentensis, and grapevines. Detected in 2015, it causes Pecan Bacterial Leaf Scorch (PBLS), leading to leaf scorch, necrosis, and branch dieback, which reduce yields and increase management costs (Hilton et al., 2017). Chitalpa trees, initially thought to be stressed, were found infected, suggesting spread through nursery stock (Randall et al., 2009). A new subspecies, X. fastidiosa subsp. tashke, has also been identified, complicating control efforts (University of Arizona). The pathogen threatens the grape industry by causing Pierce’s Disease, resulting in vine death and poor grape quality. Proactive management and research are essential to control the pathogen and prevent its spread (Randall et al., 2009; Hilton et al., 2017).

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Arkansas

The presence of Xylella fastidiosa is a growing concern in Arkansas, affecting a wide range of plants, including grapevines, oaks, maples, and redbuds (Smith, 2013). This bacterium causes serious diseases like Pierce’s Disease and Bacterial Leaf Scorch, leading to browning leaves, stunted growth, and plant death if unmanaged. Grapevines, especially in Northwest Arkansas, are severely impacted by Pierce’s Disease, threatening local grape industries (Smith, 2013). Research into resistant varieties such as the Southern Sensation Seedless grape offers hope, demonstrating strong resilience even in regions heavily affected by Xylella (American Vineyard Magazine, 2025). However, continued vigilance is critical. Early detection, insect control, and effective management practices remain essential to contain the spread, particularly as sap-sucking insects like leafhoppers and spittlebugs contribute to rapid transmission (Smith, 2013). Without sustained action, Xylella fastidiosa poses a significant threat to Arkansas' agricultural health and economy

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California

Xylella fastidiosa has firmly established its presence across California, affecting vital crops and threatening the state's agricultural economy. Studies confirm infections in pecan orchards (Hilton et al., 2017), olive trees (Krugner et al., 2014), and urban mulberry species (Hernandez-Martinez et al., 2006). The bacterium also causes severe diseases like Pierce’s Disease in grapevines (Raju et al., 1983) and Almond Leaf Scorch Disease (Krugner et al., 2012), impacting billion-dollar industries. The primary spread occurs through sharpshooter vectors, with the glassy-winged sharpshooter playing a key role (Beal, 2021). Management strategies, including insect control, removal of infected plants, and resistant crop development, are critical (Shapland et al., 2006). Without aggressive intervention, Xylella fastidiosa could cause lasting damage to California’s agricultural systems. Continued research and proactive measures remain essential to safeguard the state's future.

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Dakota (North and South Dakota)

Although Xylella fastidiosa (Xf) has not yet established itself in Dakota, its presence in neighboring Oklahoma and Nebraska raises serious concerns. Recent findings show Xf infecting grapevines in Oklahoma and cold-tolerant strains thriving in Nebraska’s mulberry trees (Galvez et al., 2010). Research suggests that Xf is adapting to colder climates, meaning Dakota’s fluctuating temperatures may no longer offer natural protection. Climate change and the pathogen’s resilience could put Dakota’s expanding vineyards and other crops at risk. Vigilant monitoring, early detection, and proactive disease management are critical to safeguard the region’s agricultural future (Galvez et al., 2010).

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Delaware

Xylella fastidiosa has been confirmed in Delaware, especially affecting urban oak trees. Early research by Sherald and Kostka (1992) identified oak leaf scorch caused by Xylella fastidiosa, primarily impacting red, black, and pin oaks. Further studies, including Gregory and Pollok (2025), confirmed the disease's ongoing presence and the availability of diagnostic testing across the state. Sherald (2007) emphasized Delaware's shared environmental risks with neighboring states like Pennsylvania and New Jersey, warning that oaks, elms, and sycamores remain highly vulnerable. According to a USDA Forest Service report (Potter, 2017), red oak mortality due to bacterial leaf scorch (BLS) reached 2.1%, doubling the state’s average tree mortality rate. Leafhoppers, spittlebugs, and alternative hosts like wild grapevines (Sherald, 2007) complicate efforts to control the spread. With forests covering about 355,000 acres, the environmental and economic risks are significant. Xylella fastidiosa is already here. Proactive monitoring, early detection, and management are critical to protecting Delaware’s forests and urban trees from further loss.

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District of Columbia (D.C.)

Research clearly shows the strong presence of Xylella fastidiosa in Washington D.C.'s urban forest. A six-year study of American elms found infection rates jumped from 21% to 60%, with severe leaf browning and crown dieback (Sherald et al., 1994). Further studies confirmed X. fastidiosa subsp. multiplex as the dominant strain across over 20 tree species, including oaks and sycamores (Harris, 2014; Harris et al., 2014). Silent infections in asymptomatic trees highlight the hidden spread of the disease. Alarmingly, 88 out of 95 surveyed sites tested positive, and infections were found across almost all city wards (Harris et al., 2014). With climate stress and urban challenges, proactive monitoring and public awareness are critical to protecting D.C.'s trees from this persistent pathogen.

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Florida

The presence of Xylella fastidiosa (XF) in Florida is a confirmed and serious concern, affecting a wide range of plants. Research has documented XF infections in southern highbush blueberries (Harmon and Hopkins, 2009), oleanders along highways (Wichman et al., 2000), and oaks in both forest and urban settings (Barnard et al., 1998). In citrus groves, the glassy-winged sharpshooter, a major vector of XF, has been widely detected, posing a continued threat (Hall and Hunter, 2008). Stone fruits such as almonds, peaches, and apricots also show significant infection rates (Matsumoto et al., 2023). Grapevines, especially ‘Chardonnay’, suffer from Pierce’s Disease caused by XF (Huang and Lu, 2002). Although not yet confirmed in Florida, the state’s conditions are favorable for XF host shifts to mulberries (Nunney et al., 2014). These findings highlight an urgent need for continued monitoring and the development of resistant plant varieties to protect Florida’s agriculture.

 

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Georgia

Multiple studies confirm the presence and threat of Xylella fastidiosa (Xf) in Georgia. Initially detected in southern highbush blueberries (Chang et al., 2007; Oliver et al., 2021), Xf was later found in red oaks (Chen et al., 2013) and pecans, with over 60% infection rates in surveyed orchards (Bock et al., 2018). Recent discoveries also confirmed Xf in Southern Shagbark Hickory (Bock et al., 2025) and American elms (Ali et al., 2020), highlighting its spread beyond crops to ornamental trees. Genetic studies reveal that Georgia strains of Xf are evolving separately from those in neighboring states (Oliver et al., 2021), raising concerns about long-term management. The pathogen survives mild winters (Chang et al., 2009), increasing its persistence and spread risk. The evidence is clear: Xf is not isolated to a single crop or area. It poses a statewide threat to agriculture and forestry,

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Hawaii

In December 2022, Xylella fastidiosa subsp. sandyi was officially detected in oleander plants in Kula, Hawaii. Infected plants showed symptoms like leaf scorch, wilting, stunted growth, and necrotic leaf spots (Lutgen et al., 2024). PCR and qPCR testing confirmed the presence of the bacterium, matching it 100% with known strains OC8 and Ann-1 (Lutgen et al., 2024). This marks the first confirmed case of X. fastidiosa in Hawaii, raising major concerns for ornamental plants, native species, and agriculture. Given the devastating impact of this pathogen elsewhere, quick action is critical to prevent widespread damage. Researchers used reliable detection methods following Harper et al. (2010) and Li et al. (2008), ensuring the accuracy of the findings. The infection in Hawaii highlights how easily plant diseases can spread through imported plants, threatening biodiversity and plant health across the islands. Immediate surveillance and control measures are needed to contain this serious threat.

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Illinois

Extensive research confirms the presence of Xylella fastidiosa (Xf) across Illinois, affecting oaks, sycamores, maples, and even fruit crops. Between 2000 and 2005, 28 positive cases of bacterial leaf scorch (BLS) were recorded in oaks across multiple counties (Pataky, 2005). Sycamores in both urban and wild settings have also been impacted (Leininger et al., 1999). Recent studies highlight the increasing threat to red oaks, pin oaks, and maples, worsened by warmer weather and climate change (Pankau, 2020; Progressive Tree Service, n.d.). Cold winters no longer guarantee protection, as Xf survives in plant tissues and resurges each spring (Progressive Tree Service, n.d.). Forest monitoring confirmed the bacterium’s presence in hardwood trees (Adams et al., 2010), while infections in peach orchards point to its expanding range (Overall & Rebek, 2017). Urban shade trees are particularly vulnerable, with symptoms often mistaken for drought stress (Plewa & Cleveland, 2017). With clear evidence from multiple studies, it’s crucial for Illinois residents and land managers to prioritize early testing and management strategies to combat this growing threat.

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Indiana

Scientific studies confirm the presence of Xylella fastidiosa (Xf) in Indiana, posing a threat to native and urban trees. The first detection occurred in pin and bur oaks in Spencer County (Hartman et al., 1995). Later research found the bacterium in oaks, sycamores, and wild Carya species across the state (Adams et al., 2008; Hilton et al., 2020). Urban surveys confirmed infections in shade trees like oaks and maples, often misdiagnosed as drought stress (Starbuck, 2010). Alarmingly, a unique Indiana strain, ST50, was discovered in white ash trees (Nunney et al., 2013), suggesting hidden infections could be more common. Climate change may worsen the situation, helping Xf survive winters and spread further (Bartlett Tree Experts, 2025; Pankau, 2020). While grapevines have not been heavily affected yet, studies warn Indiana’s climate puts vineyards at future risk (Riaz et al., 2020). With some trees acting as symptomless carriers, early detection, monitoring, and proactive management are critical to protecting Indiana’s landscape.

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Kansas

The presence of Xylella fastidiosa (Xf) in Kansas has been confirmed through positive samples collected from various counties (Starbuck, 2010). Symptoms of bacterial leaf scorch (BLS), such as marginal leaf burn and halo effects, have been observed in red oaks, pin oaks, sycamores, sugar maples, mulberries, elms, and hackberries. Although large-scale surveys are lacking, diagnostic tests confirm infections, suggesting that many cases may be going unreported due to limited testing access (Starbuck, 2010). Urban areas like Topeka, Wichita, and Kansas City could face significant environmental and economic losses if infected trees continue to decline. Mature trees provide essential benefits like cooling, air quality improvement, and increased property values. The risk also extends beyond trees. If Xf spreads to agricultural crops or nursery plants, Kansas’s farming economy could be impacted (Robinson, n.d.). While the state is not yet facing a full-blown crisis, early detection, monitoring, and proactive management are critical steps to prevent a larger outbreak.

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Kentucky

Multiple studies have confirmed the presence of Xylella fastidiosa (Xf) in Kentucky, posing a major threat to agriculture and urban trees. The first detection occurred in pin oaks in Lexington (Hartman et al., 1991), later spreading to other cities and species like maples and sycamores (Gauthier, 2021). In 2015, Xf was also confirmed in blueberries, with infected plants showing browning, defoliation, and rapid decline (Leonberger & Gauthier, 2015). Further genetic analysis revealed that Xf strains have adapted to local plants, with unique types even found in ash trees (Nunney et al., 2013). Worryingly, both symptomatic and asymptomatic infections have been detected in grasses like Kentucky bluegrass and tall fescue, suggesting silent spread (Mundell, 2005). This hidden threat could make early detection challenging and increase long-term risks. With no cure available, Kentucky faces serious economic and environmental costs if Xf continues to spread. Awareness, early diagnosis, and proactive management are critical to protect crops, forests, and urban landscapes

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Louisiana

Xylella fastidiosa (Xf) has been confirmed in multiple plants across Louisiana, threatening both the environment and the economy. The first major detection came in 2010 when oleander plants in Baton Rouge and Thibodeaux were found infected with Xf subsp. sandyi (Singh et al., 2010). Symptoms included leaf yellowing, drying, and plant death. Further studies revealed that rabbiteye blueberries, common across Louisiana, can silently carry and spread three different Xf strains, including two new ones discovered in the state (Ferguson et al., 2020). This silent spread poses a serious risk to nearby farms and wild plants. Pecan trees, a vital crop, have also been hit. Infected trees showed leaf scorch, early leaf drop, and reduced nut size due to Xf subsp. multiplex (Melanson et al., 2012). Insects and infected grafts can spread the bacteria rapidly across orchards. The evidence is clear: Xf is already impacting Louisiana’s crops and landscapes. Early detection, monitoring, and strong management strategies are critical to prevent further damage

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Maryland

Xylella fastidiosa (Xf) has been confirmed in multiple plants across Maryland, with significant implications for both agriculture and urban landscapes. The first genomic data on Xf strains infecting landscape trees was found in mulberry trees in Beltsville, where a unique strain, Mul-MD, was identified (Guan et al., 2014). This discovery is vital, as it expands the known host range and emphasizes the need for increased surveillance and management in urban areas. A separate study revealed that Maryland’s commercial nursery plants, including crape myrtle, Japanese stewartia, and mimosa, can harbor Xf asymptomatically, complicating efforts to control its spread (Huang, 2007). Insect vectors, such as sharpshooters and spittlebugs, play a critical role in spreading the bacterium, making targeted pest control essential in nurseries and agricultural settings. Maryland faces growing challenges with Xf, as it infects both ornamental and agricultural plants. Early detection, insect control, and ongoing monitoring are key to mitigating its impact on the state’s plant health..

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Minnesota

The pathogen commonly found in warmer southern states, has recently raised concerns about its potential spread to colder regions like Minnesota. Historically, Minnesota’s harsh winters acted as a natural barrier to this pathogen (Adams et al., 2009). However, with climate change leading to milder winters, the state may no longer be immune. Recent studies reveal a more complex picture. Adams et al. (2009) observed that although no trees tested positive for the pathogen in Minnesota, there’s a possibility of undetected low concentrations in northern hardwoods. Moreover, a study by Mundell (2005) confirmed the presence of Xylella fastidiosa in the state for the first time, with strains genetically similar to those found in Kentucky. This suggests that the pathogen may have been present for longer than initially thought. With rising temperatures, Minnesota faces an increased risk of this pathogen spreading, which could damage valuable tree species such as oaks and maples and threaten crops like grapes. Continued monitoring and early detection are crucial to mitigate the impact of Xylella fastidiosa in the region.

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Mississippi

Xylella fastidiosa has been present in Mississippi since the 1950s, significantly affecting the grape industry. The humid and hot climate of the state, coupled with the prevalence of sharpshooter insects, accelerates the spread of the pathogen. This has resulted in reduced grape production, affecting both the quantity and quality of crops. Recent studies have deepened our understanding of the pathogen's presence in Mississippi. Mavrodi et al. (2020) sequenced the genomes of three Xylella strains isolated from southern Mississippi, confirming the presence of the disease and revealing its genetic diversity. Meanwhile, Stafne et al. (2024) found that the OK392 grape cultivar, although highly susceptible to Pierce’s disease, demonstrated resilience in areas with significant disease pressure. These findings highlight the ongoing challenges for Mississippi’s agricultural sector.

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Missouri

Xylella fastidiosa has been steadily spreading in Missouri, raising concerns for both urban and agricultural sectors. The pathogen's emergence in previously unaffected areas is alarming, with bacterial leaf scorch (BLS) affecting trees like red mulberry and red maple (Sherald and Kostka 1992). In addition, Pierce's disease, caused by Xylella, was first reported in Missouri vineyards in 2013, contributing to the loss of grapevines (Jones 2014). The pathogen has also impacted peach orchards, leading to concerns over Phony Peach Disease (Summerfruit NZ 2022), and is increasingly affecting oak trees, with BLS identified as a significant contributor to tree health decline (Mathias Precision Tree Service 2025). Research confirms Xylella's growing presence across various Missouri counties, such as St. Louis and Boone (Starbuck 2010). As the pathogen continues to spread, it is essential for residents, farmers, and arborists to stay informed and take proactive measures. Early detection and research into management strategies are vital to mitigating this emerging threat and protecting Missouri’s tree populations for the future.

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Montana

Xylella fastidiosa has been detected in Montana, though its spread remains limited. A study by the U.S. Forest Service’s Forest Health Monitoring Program (2008-2009) identified a positive sample from urban, rural, and forested areas, confirming the presence of the bacterium. Despite the low detection rate, the warming climate and increasing insect vectors raise concerns for the future spread of Xylella in the state. The bacterium is responsible for several plant diseases, including Bacterial Leaf Scorch (BLS), which affects trees like oaks and maples, and Pierce’s Disease, which threatens grape production. Warming temperatures, particularly in USDA Hardiness Zones 6 and 7, could expand the reach of these diseases, with long-term implications for Montana’s forestry and agriculture sectors (Adams et al., 2011). While the risk remains moderate, continuous monitoring and early detection are critical to managing this growing threat and preventing further spread of Xylella fastidiosa in Montana's landscapes.

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Nebraska

Xylella fastidiosa (Xf) has increasingly been identified as a serious concern in Nebraska, with notable research indicating its presence and impact on both urban and agricultural landscapes. In 2010, Christopher J. Starbuck highlighted the pathogen's presence in Nebraska through samples that tested positive for Xf, despite challenges in diagnosis due to symptoms resembling environmental stresses (Starbuck, 2010). Furthermore, in 2015, a study by Guan et al. confirmed the detection of Xf strains in mulberry trees in Nebraska using PCR technology, marking a significant milestone in understanding its spread (Guan et al., 2015). Additionally, an evolutionary study by Chen et al. (2002) revealed that strains of Xf found in Nebraska are closely related to those causing Pierce's Disease in southern U.S. grapevines, underscoring the pathogen's adaptability to varying climates. With diseases like Bacterial Leaf Scorch and Mulberry Leaf Scorch now present in Nebraska, urgent action is needed to improve diagnostic methods.

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Nevada

Xylella fastidiosa, a destructive plant pathogen, has emerged as a significant threat to Nevada's agriculture. Studies, including one by Frankel (2002), have confirmed the pathogen’s presence in key agricultural areas such as Clark County and Washoe County. The bacterium, which causes diseases like Pierce’s disease in grapevines, has been detected in vineyards, orchards, and even native plants. Despite Nevada’s dry climate, warming trends and changing environmental conditions have allowed Xylella fastidiosa to thrive (Frankel, 2002). The impact on agriculture is severe, with affected plants showing symptoms like wilting, leaf scorch, and stunted growth, leading to reduced crop yields and long-term ecological consequences. Vineyards, central to Nevada’s growing wine industry, are particularly vulnerable. Insect vectors, especially sharpshooters, play a critical role in spreading the pathogen, further exacerbating its reach.

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New Hampshire

Xylella fastidiosa poses a growing threat to agriculture in New Hampshire, with its presence confirmed in several studies. The pathogen, which affects crops like grapevines, is a concern for the state's agricultural industry. Research from the European Food Safety Authority (EFSA, 2017) highlights the detection of Xylella in the northeastern U.S., including New Hampshire, and points to vector insects, particularly from the Cicadellidae family, as key transmitters. This pathogen's potential to spread through these insects makes it essential for farmers and plant health experts to monitor its movement. Vigilant surveillance and proactive measures are crucial to protecting New Hampshire’s agricultural sector, especially grapevine production, from further damage.

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New Jersey

Xylella fastidiosa pose a significant threat in New Jersey, particularly affecting oak trees. A study by Gould et al. (2004) reported that 30-35% of oak trees in affected communities showed symptoms of bacterial leaf scorch (BLS), leading to estimated economic losses between $0.7 and $1.6 million due to tree removal and replacement. Further research by Zhang et al. (2011) identified treehoppers as key insect vectors, with 13.89% of insects tested carrying the pathogen. Recent findings by Iskra et al. (2025) highlighted rapid declines in infected oak trees, emphasizing the long-term costs of managing the disease and its environmental impact. Effective pest control, early detection, and continued research are critical to mitigating the spread of Xylella fastidiosa in New Jersey (Gould et al., 2004; Zhang et al., 2011; Iskra et al., 2025).

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New Mexico

Xylella fastidiosa presence threat to New Mexico's agriculture, impacting key crops such as pecans, peaches, grapes, and ornamental plants. First detected in pecans in 2015, pecan bacterial leaf scorch (PBLS) has spread across commercial and native orchards, resulting in reduced yields and increased management costs (Olsen, 2015). Similarly, the pathogen was found in peach trees in 2010, causing deformities and dieback (Randall et al., 2011). Grapevines in New Mexico were affected by Pierce's disease starting in 2006, threatening the local wine industry (Randall et al., 2007). Recent findings also indicate a novel subspecies in Chitalpa trees, complicating management efforts (Randall et al., 2009). The spread of Xylella fastidiosa necessitates ongoing research and robust control measures to safeguard the state's agricultural economy (Hilton et al., 2017).

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New York

Xylella fastidiosa, impacting urban trees, poses a growing risk to New York's urban and agricultural landscapes. Studies show the spread of Bacterial Leaf Scorch (BLS) in urban environments, particularly in tree species like oak, sycamore, and elm (Hartman et al., 1995; Harris et al., 2014). New York, with similar urban conditions to Washington, D.C. and Kentucky, faces a potential outbreak. Confirmed presence of Xylella in the state, especially in red oak and sycamore trees, is alarming (Parkinson & Malumphy, 2015). Additionally, the recent detection of Mulberry Leaf Scorch (MLS) in southern New York highlights the growing threat (Kostka et al., 1986). Immediate action through monitoring and early detection is essential to mitigate the spread of this damaging pathogen.

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North Carolina

Xylella fastidiosa (Xf) carrying a threat to various crops and ecosystems in North Carolina. Studies over the years have highlighted its presence across vineyards, blueberries, and sycamore trees. Research has shown that certain weeds and grasses, such as fescue and wild strawberry, can act as reservoirs for Xf, necessitating vegetation management to prevent disease spread (Floyd & Sutton, 2007). Additionally, the pathogen is a major threat to southern highbush blueberries, with a distinct strain found in the state (Oliver et al., 2021). Sycamore trees are also affected by Xf, indicating its broader ecological impact (Haygood et al., 1988). Effective management of insect vectors, such as leafhoppers, remains critical in controlling Xf’s spread in vineyards (Myers et al., 2007). These findings underscore the need for region-specific strategies to mitigate the threat of Xf in North Carolina.

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Ohio

Xylella fastidiosa, responsible for Bacterial Leaf Scorch (BLS), has recently been confirmed in Ohio, marking its spread into the Midwest (Starbuck, 2010). Research from Michigan State University highlighted the pathogen’s presence in various oak species, including swamp white oak, in St. Louis and St. Charles counties (Starbuck, 2010). The disease, characterized by leaf scorch starting at the margins, affects trees like sycamore, mulberry, and oaks, especially in drought conditions. Leafhoppers, which spread the bacterium, contribute to the disease's unpredictable outbreaks. With limited management strategies, early detection and prevention are essential to mitigate its impact on Ohio’s forestry and agriculture.

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Oklahoma

Xylella fastidiosa (XF) has been a growing concern in Oklahoma, with its presence confirmed in multiple plant hosts across the state. Initially detected in elm trees in 2004 (Olson et al., 2006), the bacterium spread to grapevines by 2008 (Smith et al., 2009). Surveys from 2016-2017 revealed XF in various counties, including Atoka, McCurtain, and Cleveland, highlighting its statewide impact (Wallace, 2018). Insects such as Graphocephala versuta have been identified as major vectors, facilitating the spread of XF among plants (Overall, 2013; Overall & Rebek, 2015). The disease threatens agriculture and must be managed through heightened awareness and effective control measures.

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Oregon

Xylella fastidiosa was first detected in Oregon in 2015, marking a significant agricultural concern. The bacteria, found in Hood River County's pear nursery and the National Clonal Germplasm Repository in Corvallis, led to quarantines across nine counties (Perkowski, 2015). The pathogen poses a severe threat to crops such as wine grapes, pears, apples, and blueberries, all of which are susceptible to disease spread by insects like leafhoppers and sharpshooters (Eddy, 2015). Oregon's quarantine measures include plant destruction and restrictions on plant movement, crucial for protecting local and international trade (Pscheidt, 2023). As climate change warms the region, the risk of Xylella spreading could increase, particularly with the presence of vectors in key agricultural areas (Pscheidt, 2025). Ongoing monitoring and preventive actions are essential for mitigating this threat.

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Pennsylvania

Xylella fastidiosa has been confirmed in urban trees in Pennsylvania, particularly oak species. Studies in Philadelphia show infection rates of 39% in Northern Red Oak and 47.6% in Pin Oak (McElrone et al., 2008). The disease reduces tree hydraulic conductivity, leading to blockages and symptoms like "scorch" (Olszewski et al., 2014). The pathogen also affects non-oak species, including Thornless Honeylocust in Gettysburg (Loyd & Bechtel, 2019). Bacterial leaf scorch (BLS), caused by Xylella, is a slow-developing but devastating issue for urban forests. Early detection and consistent monitoring are crucial to mitigate the spread and protect Pennsylvania's trees (Mr. Tree, 2022).

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Rhode Island

Xylella fastidiosa (Xf), may pose a threat to Rhode Island's agriculture. Historical evidence from the 1950s suggests that symptoms resembling Xf infection, such as stunted growth and leaf yellowing in grapevines and lucerne, were observed (CABI, 2025). Furthermore, the presence of Draeculacephala antica, an insect vector for Xf, raises concerns about its potential transmission in the state. While direct confirmation of Xf in Rhode Island is lacking, research indicates the need for proactive surveillance and management strategies. Recent studies also show the potential of radicinin, a compound from fungi, in controlling Xf (Aldrich et al., 2015). This biocontrol agent could be an effective solution for Rhode Island's agriculture if Xf is detected. Continuous monitoring is essential to safeguard local crops from this invasive pathogen.

Read the state status: https://www.xylellafastidiosa.com/2025/04/xylella-fastidiosa-in-rhode-island.html

South Carolina

Xylella fastidiosa has been detected in both agricultural crops and urban trees in South Carolina, posing a serious threat to the state's plant life. A recent study (Cieniewicz et al., 2024) discovered X. fastidiosa subsp. fastidiosa in rabbiteye blueberries, a crop previously thought to only host the subsp. multiplex. This new strain could spread to other crops like grapes and peaches, potentially causing significant economic losses. Additionally, research by Blake (1993) confirmed widespread infection in oak, maple, and sycamore trees across the state. These findings highlight the urgency of implementing stronger surveillance and disease management strategies to protect South Carolina’s agriculture and urban landscapes from further spread.

Read the state status: https://www.xylellafastidiosa.com/2025/04/xylella-fastidiosa-in-south-carolina.html

Tennessee

Xylella fastidiosa (XF) poses a significant threat to Tennessee's agricultural and ornamental sectors. Studies reveal its presence in vineyards, ornamental plants, and fruit orchards across the state. In 2019, the University of Tennessee found XF in 25% of grapevine samples from various counties, impacting Tennessee’s grape industry with symptoms of Pierce’s Disease (University of Tennessee, 2019). A 2021 study highlighted XF’s widespread effect on ornamental plants like roses and magnolias, endangering the nursery industry (Tennessee Agricultural Extension Service, 2021). Furthermore, surveillance in 2020 detected XF in pecan orchards, raising concerns about its long-term impact on the state's nut crops (Tennessee Department of Agriculture, 2020). Insect vectors, including sharpshooters, are key in spreading the pathogen (University of Tennessee Entomology Department, 2022). Effective management and research are crucial to prevent further spread and mitigate economic losses.

Read the state status: https://www.xylellafastidiosa.com/2025/04/xylella-fastidiosa-in-tennessee.html

Texas

Xylella fastidiosa (Xf) is confirmed and great threat to Texas, impacting a wide range of plants. In Texas vineyards, particularly in the Gulf Coast, the Cynthiana grape variety has been severely affected by Pierce’s Disease, with reduced crop yields attributed to Xf (Buzombo et al., 2006). Additionally, Xf has been detected in ornamental plants like oleanders, with symptoms reported in cities such as Galveston and Austin (Huang et al., 2004). The pathogen’s genetic diversity in the state further complicates control efforts (Lin et al., 2013). Insect vectors, such as the glassy-winged sharpshooter, play a crucial role in spreading Xf (Mitchell et al., 2009), making integrated pest management essential to mitigate its spread. Continuous monitoring and management are key to protecting Texas' agricultural and ornamental sectors from further damage.

Read the state status: https://www.xylellafastidiosa.com/2025/04/xylella-fastidiosa-in-texas.html

Virginia

The presence of Xylella fastidiosa is confirmed in Virginia's agriculture, particularly its vineyards and urban trees. Research shows that the pathogen, which causes Pierce’s Disease, has spread to new regions due to rising temperatures and the proliferation of leafhopper vectors (Wallingford, 2008). Studies confirm the presence of Xylella in both grapevines and sycamore trees across Virginia, with infection rates as high as 80% in major winegrowing regions (Abdelrazek et al., 2024). The pathogen’s expansion, including the previously unknown multiplex subspecies, further heightens concerns for the viticulture industry (Guan et al., 2014). As temperatures continue to rise, the threat of Xylella fastidiosa is expected to intensify, affecting both agricultural crops and urban landscapes in Virginia.

Read the state status: https://www.xylellafastidiosa.com/2025/04/xylella-fastidiosa-in-virginia.html

Washington

Washington, D.C. has the presence of Xylella fastidiosa. Research shows the bacterium infects multiple tree species, including black oak, American elm, red oak, sycamore, and mulberry (McElrone et al., 1999; Huang, 2004; Guan et al., 2023; Harris & Balci, 2015). Studies have identified invasive plants like English ivy and oriental bittersweet as important reservoirs (McElrone et al., 1999), while genome sequencing revealed unique strain characteristics critical for diagnostics (Guan et al., 2023). The discovery of five distinct strains tied to specific tree species highlights the need for targeted disease management (Harris & Balci, 2015). With infected trees already confirmed across the city, proactive monitoring and control efforts are vital to protect Washington, D.C.’s urban forests.

Read the state status: https://www.xylellafastidiosa.com/2025/04/xylella-fastidiosa-in-washington.html

West Virginia

Xylella fastidiosa was first detected in West Virginia in 1992 on a northern red oak in Jefferson County (West Virginia Division of Forestry, 2010). Since then, it has spread to multiple counties including Berkeley, Cabell, Kanawha, Morgan, and Wood. The disease is mainly transmitted by xylem-feeding insects like leafhoppers, which thrive in West Virginia’s rich forests and urban areas. BLS damages essential water pathways in trees, leading to premature leaf drop and even death. Oaks, maples, elms, and sweetgums are among the affected species, causing growing concern across both urban and rural landscapes (West Virginia Division of Forestry, 2010). Continuous monitoring by the West Virginia Department of Agriculture and USDA Forest Service reveals the alarming rate at which this threat is spreading.

Read the state status: https://www.xylellafastidiosa.com/2025/04/xylella-fastidiosa-in-west-virginia.html

Wisconsin

Xylella fastidiosa was first confirmed in Wisconsin in 2008, detected in bur oak trees in Dane County (Wisconsin DNR, 2008). The pathogen, known for causing Bacterial Leaf Scorch (BLS), showed potential to spread across southern and central Wisconsin, threatening multiple hardwood species. Symptoms like leaf scorch and premature leaf drop weaken trees over time, making long-term monitoring essential. A follow-up study found two additional positive cases in red oaks in Wisconsin’s colder northern region, highlighting the pathogen’s ability to survive even in harsher climates (Adams et al., 2009). Although current infection levels remain low, climate change may increase the risk of future outbreaks.

Read the state status: https://www.xylellafastidiosa.com/2025/04/xylella-fastidiosa-in-wisconsin.html

 

The threat of Xylella fastidiosa is neither isolated nor diminishing. Its expanding geographic footprint and impact on vital crops require a coordinated national response. Enhanced funding for research, development of resistant plant varieties, stricter control of plant movement, and public awareness campaigns are essential. Only with immediate action, stronger research funding, resistant plant development, strict movement controls, and nationwide awareness, can the U.S. prevent economic losses, protect biodiversity, and secure the future of its agriculture.

 

 

Quick Overview: State-by-State Impact of Xylella fastidiosa

No.	State	XF Presence	Impact on Agriculture	Affected Plants	Diseases Caused
1	Alabama	Confirmed	High risk	Blueberries, Grapes, Peaches	Bacterial Leaf Scorch, Pierce’s Disease
2	Arizona	Confirmed	High risk	Pecans, Chitalpa, Grapes	Pecan Bacterial Leaf Scorch, Pierce’s Disease
3	Arkansas	Confirmed	Widespread	Grapes, Oaks, Maples	Pierce’s Disease, Bacterial Leaf Scorch
4	California	Confirmed	High risk, Widespread	Almonds, Olives, Grapes, Mulberries	Pierce’s Disease, Almond Leaf Scorch, Mulberry Leaf Scorch
5	Delaware	Confirmed	Widespread Urban Impact	Oaks, Elms, Sycamores	Bacterial Leaf Scorch
6	Florida	Confirmed	High risk	Blueberries, Citrus, Grapes, Oaks	Pierce’s Disease, Citrus Variegated Chlorosis, Oak Decline
7	Georgia	Confirmed	High risk	Pecans, Blueberries, Hickories, Oaks	Pierce’s Disease, Pecan Bacterial Leaf Scorch
8	Hawaii	Confirmed	Localized Threat	Oleander	Oleander Leaf Scorch
9	Illinois	Confirmed	Moderate	Grapes	Pierce’s Disease
10	Indiana	Confirmed	Moderate	Grapes	Pierce’s Disease
11	Kansas	Confirmed	Moderate	Grapes	Pierce’s Disease
12	Kentucky	Confirmed	Widespread	Landscape Trees, Grapes	Bacterial Leaf Scorch, Pierce’s Disease
13	Louisiana	Confirmed	High risk	Blueberries, Pecans, Oleander	Pierce’s Disease, Pecan Leaf Scorch
14	Maryland	Confirmed	Widespread Urban Threat	Mulberry, Crape Myrtle, Sassafras	Bacterial Leaf Scorch, Mulberry Leaf Scorch
15	Minnesota	Confirmed	Potential Spread (Cool Regions)	Urban Shade Trees	Bacterial Leaf Scorch
16	Mississippi	Confirmed	High risk	Grapes	Pierce’s Disease
17	Missouri	Confirmed	Moderate	Mulberry, Grapes, Maples	Bacterial Leaf Scorch, Pierce’s Disease
18	Montana	Confirmed (Limited)	Potential Spread (Cool Regions)	Urban Shade Trees	Bacterial Leaf Scorch
19	Nebraska	Confirmed	Moderate	Landscape Trees	Bacterial Leaf Scorch
20	Nevada	Confirmed	Low to Moderate	Ornamentals, Vineyards	Leaf Scorch
21	New Hampshire	Confirmed	Moderate	Grapes	Pierce’s Disease
22	New Jersey	Confirmed	Widespread Urban Impact	Landscape Trees	Bacterial Leaf Scorch
23	New Mexico	Confirmed	High risk	Pecans, Grapes, Peaches	Pecan Leaf Scorch, Pierce’s Disease
24	New York	Confirmed	Widespread Urban Threat	Landscape Trees	Bacterial Leaf Scorch
25	North Carolina	Confirmed	High risk	Blueberries	Bacterial Leaf Scorch
26	North Dakota	Risk Detected	Potential Spread (Cool Regions)	None Yet	None Yet
27	Ohio	Confirmed	Moderate	Landscape Trees	Bacterial Leaf Scorch
28	Oklahoma	Confirmed	High risk	Grapes, Elms	Pierce’s Disease, Bacterial Leaf Scorch
29	Oregon	Confirmed (Limited)	Low impact	Ornamentals, Pears	Leaf Scorch
30	Pennsylvania	Confirmed	Widespread Urban Threat	Landscape Trees	Bacterial Leaf Scorch
31	Rhode Island	High Risk	High risk	Grapevines, Alfalfa	Pierce’s Disease
32	South Carolina	Confirmed	Moderate	Grapes	Pierce’s Disease
33	South Dakota	Risk Detected	Potential Spread	None Yet	None Yet
34	Tennessee	Confirmed	Moderate	Grapes	Pierce’s Disease
35	Texas	Confirmed	Very High risk	Grapes, Pecans, Olives	Pierce’s Disease, Pecan Leaf Scorch
36	Utah	Confirmed	Low to Moderate	Trees	Bacterial Leaf Scorch
37	Vermont	Confirmed	Low to Moderate	Trees	Bacterial Leaf Scorch
38	Virginia	Confirmed	Widespread	Grapes, Sycamores	Pierce’s Disease, Bacterial Leaf Scorch
39	Washington, D.C.	Confirmed	Severe Urban Threat	Elms, Oaks, Sycamores	Bacterial Leaf Scorch
40	West Virginia	Confirmed	Moderate	Landscape Trees	Bacterial Leaf Scorch
41	Wisconsin	Confirmed	Potential Spread	Trees	Bacterial Leaf Scorch

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