Oregon is the third-largest producer of sweet cherries in the United States, supplying about 11% of the national market. The state’s sweet cherry industry was valued at $72.5 million in 2024, with most production concentrated in the Mid-Columbia region.
X-disease is a reemerging threat to that industry. The infection causes fruit to become small, flavorless and unmarketable. It spreads through root grafting and leafhopper insects, and there is no cure.
Improved detection and management of X-disease can reduce economic losses, support farm viability and protect jobs in rural communities.
Growers must remove infected trees to slow the spread, but doing so can mean immediate income loss. Without action, the disease can spread quickly and devastate entire growing regions, as seen in California during the 1980s.
The Oregon State University Extension Service has prioritized helping growers identify and manage X-disease early. Ashley Thompson, Extension fruit crops specialist and assistant professor in the Oregon State University College of Agricultural Sciences, and Niall Millar, faculty research assistant, lead research and outreach efforts.
Thompson has hosted hands-on field days focused on virus and symptom identification and shared research updates at multiple teaching events. These efforts have reached more than 1,200 growers and agricultural professionals and increased participation in X-disease research and management.
Extension resources include bilingual identification guides and practical publications that help growers recognize symptoms and respond quickly. More than 1,500 identification cards have been distributed to farmers and farmworkers in Wasco County, along with 1,000 bilingual information packets developed with Washington State University.
Advancing research and management
Thompson’s program has secured more than $186,000 in funding from regional partners to study the spread of X-disease, evaluate replant strategies and identify rootstocks that may reduce risk.
This work has supported the identification of 60 infected orchards in Wasco County through grower reports and laboratory analysis. Findings also show that fumigation — a costly preplant practice — may not be necessary, and that using disease-free planting stock is the most effective prevention strategy.
Recent research is focused on improving early detection. Because symptoms are often not visible until the disease has spread, researchers are exploring new tools to identify infected trees sooner.
In 2024, Thompson’s team tested a multispectral device to detect differences between infected and healthy trees but did not find clear signals. In 2025, the team expanded the effort using a hyperspectral imaging system capable of capturing a wider range of wavelengths. Researchers collected high-resolution images of cherry trees over time to detect subtle changes that may indicate infection before symptoms appear.
The project also includes collaboration with OSU engineering faculty and Washington State University. Researchers are also testing additional detection methods, including trained dogs and laboratory analysis, to better understand how to identify the disease early and reliably.
Exploring new detection tools
Early detection remains a key challenge. Current diagnostic methods, such as PCR testing, can miss infections because the pathogen may only be present in part of a tree. That means multiple samples are often needed to confirm infection.
Researchers are working to determine whether visual signals of X-disease exist that could be detected with imaging tools. If successful, hyperspectral cameras or drone-based systems could allow growers to scan entire orchards quickly and identify infected trees before symptoms are visible.
This work is still in the analysis stage, but it builds new partnerships with technology providers and expands the tools available for future research and management.
Public value
By combining research, outreach and regional collaboration, OSU Extension is helping protect a key agricultural industry in Oregon.
Improved detection and management of X-disease can reduce economic losses, support farm viability and protect jobs in rural communities.
New tools and shared knowledge also position growers to respond more quickly to emerging threats and sustain cherry production in the Pacific Northwest.