U.S.-funded UNH researchers begin studying a Fusarium disease threatening cold-hardy grapevines

A federally funded research team at the University of New Hampshire is starting a study of an emerging grapevine disease linked to Fusarium fungi that researchers say is affecting cold-hardy vines in northern U.S. growing regions and has already been associated with vineyard decline and yield losses.

The university announced on Thursday, November 5, that the project had received support from the U.S. Department of Agriculture’s National Institute of Food and Agriculture. The study, titled “Exploring Fusarium Trunk Decline, an Emerging Threat to Cold-Hardy Grapevines in the U.S.,” 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.

The work focuses on a grapevine trunk disease associated with species in the genus Fusarium. Fusarium fungi are already known as pathogens in many crops, but their role in decline affecting cold-hardy grapevines remains poorly understood. Researchers are trying to answer basic questions about where the disease-causing populations come from, how and when they enter grapevines, and how they can be detected early enough to help growers act before losses deepen.

The issue matters beyond plant pathology because cold-hardy grapes support a growing wine business across the northern Midwest, Great Lakes and Northeast. Those grapes are the base of a $400 million industry that includes wine production and agritourism, according to the university. If disease cuts yields or weakens vineyard health, it could create added pressure for wineries and other businesses tied to grape production in colder states.

UNH said previous vineyard surveys recovered Fusarium species from declining grapevines, and follow-up pathogenicity studies showed that some of those isolates can cause disease in both cold-hardy hybrid grapes and Vitis vinifera cultivars, the species that includes many traditional wine grapes. The university said substantial yield losses have been documented in affected vineyards, increasing pressure to understand the biology, spread and management of the disease.

The new project will expand earlier research across the Midwest, Great Lakes and Northeast. According to UNH, the team plans to map the geographic distribution of Fusarium populations tied to grapevine trunk disease and examine their genetic diversity. The researchers also plan to test how strongly different populations cause disease, assess their mycotoxigenic potential, improve diagnostic methods and study factors that may influence how the disease develops and how it can be managed.

Slack said one of the central questions is how common the problem really is. In comments released by the university, she said researchers already had data from the Midwest and had also been in contact with vineyards in New Hampshire reporting similar problems. She said Fusarium had been found inside local samples.

The researchers said faster diagnosis is a major need for growers. Slack said it can currently take almost two months to determine whether the Fusarium present in a vine is the pathogenic type because some species found in wood are not causing disease. The goal, she said, is to develop a quicker way to tell growers whether harmful Fusarium is present so they can make management decisions sooner.

Yuan said the project is not expected to eliminate the disease entirely, but is intended to help growers manage it more effectively. That could be especially important in northern grape regions where cold-hardy varieties have helped expand vineyard acreage and local wine production. Because the disease appears to affect both cold-hardy hybrids and Vitis vinifera, the findings could be relevant to a wider range of vineyards than those focused only on hybrid grapes.

The university linked the research to the broader economic role of wine in New Hampshire. Citing WineAmerica’s 2025 Economic Impact Study, UNH said the state’s wine industry supports an estimated 154,500 winery-related visits each year and generates about $29.5 million in tourism spending. Any disease that reduces vineyard productivity could have effects that reach beyond growers, including tasting rooms, rural tourism operators and businesses that depend on wine traffic.

UNH said the project brings together researchers from the university, Kristi Gdanetz MacCready of the USDA Agricultural Research Service, Extension specialists, diagnostic laboratories and grape growers across the region. The university said results will be shared with growers and other industry professionals through Extension programs, publications, diagnostic resources and regional outreach.

The research is intended to give growers more practical tools for early disease recognition and science-based management, at a time when vineyards in colder parts of the country are facing a threat that researchers say is emerging but still not well defined.