UNH launches study of Fusarium trunk decline in cold-hardy grapevines

An emerging threat to northern vineyards

The University of New Hampshire announced on November 5 that a federally funded team had begun studying an emerging grapevine disease linked to Fusarium fungi. The project, “Exploring Fusarium Trunk Decline, an Emerging Threat to Cold-Hardy Grapevines in the U.S.,” is supported by the US Department of Agriculture’s National Institute of Food and Agriculture.¹

The research is led by Xiaochen Yuan, an assistant professor, and Suzanne Slack, an adjunct research faculty member, both in UNH’s Department of Agriculture, Nutrition, and Food Systems. It focuses on a trunk disease associated with species of the genus Fusarium, pathogens already known in numerous crops but whose role in the decline of cold-hardy grapevines remains poorly understood.¹

Researchers aim to determine where disease-causing populations originate, when and how they enter vines, and how harmful infections can be detected before losses worsen. Previous vineyard surveys recovered Fusarium species from declining vines, while subsequent pathogenicity studies found that some isolates could cause disease in both cold-hardy hybrid grapes and Vitis vinifera cultivars. Substantial yield losses have been documented in affected vineyards.¹

Mapping the disease and shortening diagnosis

Building on earlier work, the project will investigate vineyards across the Midwest, Great Lakes and Northeast. The team plans to map the geographic distribution and genetic diversity of Fusarium populations associated with grapevine trunk disease, compare the ability of different populations to cause disease, assess their potential to produce mycotoxins, improve diagnostic methods, and study factors that may affect disease development and management.¹

Slack said establishing the prevalence of the problem is a central question. Researchers already have data from the Midwest and have heard from New Hampshire vineyards experiencing similar symptoms; Fusarium was also detected inside samples collected locally.¹

Diagnosis currently can take almost two months because some Fusarium species found in grapevine wood do not cause disease, Slack said. The researchers want a faster method that distinguishes pathogenic Fusarium and allows growers to make management decisions sooner.¹

Yuan said the project is not expected to eradicate the disease, but should help growers manage it more effectively. Although the work centers on cold-hardy grapes, evidence that the disease can affect both hybrids and Vitis vinifera means its findings may be relevant to a broader range of vineyards.¹

Economic importance and industry cooperation

Cold-hardy grapes underpin a growing wine and agritourism sector across northern US regions. UNH values the associated industry at $400 million and warns that lower yields or weakened vineyards could put additional pressure on wineries and other businesses dependent on grape production in colder states.¹

UNH also placed the research in the context of New Hampshire’s wine economy. Citing WineAmerica’s 2025 Economic Impact Study, the university said the state records an estimated 154,500 winery-related visits annually and about $29.5 million in tourism spending. Reduced vineyard productivity could therefore affect tasting rooms, rural tourism operators and other businesses that rely on wine-related visitors, as well as growers.¹

The project includes UNH researchers, Kristi Gdanetz MacCready of the USDA Agricultural Research Service, Extension specialists, diagnostic laboratories and growers across the region. Findings will be distributed to growers and other industry professionals through Extension programs, publications, diagnostic resources and regional outreach, with the objective of providing practical tools for early recognition and science-based management of a threat that is emerging but not yet clearly defined.¹