New grape studies point to tools that could shield vineyards from erratic winter weather

Researchers at the American Society for Enology and Viticulture’s national conference on Thursday presented new findings on grape breeding, dormancy management and cold hardiness that could help growers adapt vineyards to disease pressure and more erratic winter weather.

The one-hour session in the Grand Ballroom 100B brought together work from the University of Arkansas, Brock University in Canada and North Dakota State University. The studies focused on three linked challenges for grape production: developing disease-resistant grapes with acceptable consumer appeal, reducing freeze damage through plant growth regulators, and identifying genetic markers tied to budbreak and cold tolerance.

A team led by Renee Threlfall of the University of Arkansas reported consumer sensory results for Vitis × Muscadinia wide hybrids, part of a 33-person, 12-institution project supported by USDA’s National Institute of Food and Agriculture through SCRI grant #2024-51181-43236. Muscadinia grapes, grown widely in the Southeast, are known for resistance to many pathogens that affect Vitis grapes.

In 2025, the researchers evaluated 20 fresh-market Muscadinia and Vitis × Muscadinia genotypes from breeding programs in Arkansas, Georgia and North Carolina in a consumer study at the University of Florida in Gainesville. Four sensory panels of 130 consumers each assessed visual, texture and taste traits across five genotypes per panel. The study also measured physical and compositional traits and collected demographic data and grape purchasing habits.

Among participants, 65% were female, 53% were ages 22 to 34, 45% held a graduate degree, 95% had consumed bunch grapes and 71% had consumed Muscadine grapes. The researchers said 28% consumed Muscadines four to 10 times a year and 53% said they were likely to purchase them.

Genotype affected all physical and composition attributes in the trial. Berry weights ranged from 2.8 grams to 18.1 grams. Twelve of the 20 genotypes fell within what the researchers described as the ideal soluble solids-to-titratable acidity ratio range of 16 to 70. Mighty Fine had the highest flavor and overall liking scores, while Altus had the highest appearance liking; both are seeded Muscadine grapes released by the University of Arkansas System in 2023. JB12-12-A14-29, a seedless selection from Gardens Alive!, received the highest skin texture liking score, and AM-303, a University of Arkansas System selection, ranked highest for pulp texture liking.

The Arkansas team said the results could support efforts to introduce disease-resistant cultivars with stronger fruit quality. That matters beyond table grapes because breeding decisions that improve resilience to pathogens and climate stress can also shape long-term planting choices across the beverage sector, where growers need varieties better suited to changing conditions.

James Willwerth of Brock University presented six seasons of work on abscisic acid, or ABA, analogues as a way to maintain dormancy and improve cold hardiness in grapevines exposed to unstable winter temperatures. His team tested two compounds, 8′-acetylene ABA and tetralone ABA, from 2017 through 2023 on postharvest Merlot and Marquette vines at concentrations of 1.00, 0.50 and 0.25 grams per liter. The treatments were compared with S-ABA and untreated controls.

The study examined cold hardiness and deacclimation using differential thermal analysis, tracked budbreak timing based on first visible leaf tips, and measured fruit composition at harvest through soluble solids, pH and titratable acidity.

According to the researchers, the ABA analogues variably improved cold tolerance and resistance to deacclimation across six dormant seasons, especially in late winter. Budbreak was consistently delayed in Marquette, while Merlot responses varied more by season. The team found that both 8′-acetylene ABA and tetralone ABA promoted and maintained cold hardiness and delayed budbreak, while S-ABA did not affect dormancy maintenance or budbreak timing. Effects on fruit composition were minimal even when budbreak delays were significant.

Willwerth’s group said the results suggest ABA analogues could become practical tools for reducing cold-related losses in vineyards, although performance depends on genotype and seasonal conditions. The work was supported by Ontario Grape and Wine Research Inc., the Canadian Grapevine Certification Network, Agriculture and Agri-Food Canada’s Sustainable CAP Agri-Science Cluster, and Ontario’s Marketing and Vineyard Improvement Program.

In another presentation, Hava Delavar of North Dakota State University described genetic analysis of budbreak and cold hardiness in an interspecific F1 grapevine population derived from a cold-hardy Vitis riparia parent and the cold-sensitive Vitis vinifera cultivar Fresno Seedless. The trial was conducted in Fargo using an alpha-lattice design with three replications.

The researchers used rhAmpSeq markers for genotyping and identified 1,235 polymorphic loci. After quality filtering, 642 loci were retained for linkage map construction. The resulting map covered all 19 grape linkage groups across 1,023 centimorgans with an average marker interval of 1.62 centimorgans.

Cold hardiness was measured with differential thermal analysis and showed wide variation in lethal temperature exotherm values among progeny. The team found that vines with stronger midwinter cold hardiness were not consistently the same vines with greater spring frost tolerance. They also observed substantial variation in deacclimation behavior and budbreak progression across the population.

Delavar said combining those phenotypic results with a high-density linkage map offers a starting point for understanding the genetic architecture behind cold hardiness and budbreak. For growers and breeders serving wine regions in cool or variable climates, that kind of marker-based selection could eventually guide planting decisions toward varieties less exposed to frost damage as temperature swings become more common.

Together, the studies underscored how grape breeding is moving beyond yield or fruit chemistry alone toward a broader focus on climate adaptation, disease resistance and market acceptance. For wine producers and other grape-based beverage businesses, those tools may help lower production risk while expanding the range of cultivars that can succeed in colder or less predictable growing regions.