Adaptive Pruning of Cold-Hardy Commercial Wine Grape Cultivars

View the project final report

Commodities

• Fruits: grapes

Practices

• Crop Production: Pruning
• Farm Business Management: labor/employment

Several cold-hardy wine grape cultivars have been released from breeding programs and now form the foundation of the wine grape industry across many North Central Region states. While their cold tolerance and wine quality are well-documented, there is limited research on their cultivar-specific viticulture practices.  As prices of grapes stagnate, more information is needed on how to efficiently grow these cultivars.

Cold-hardy grape growers often operate in regions with high rainfall, increasing the risk of fungal diseases. Pruning, one of the most labor-intensive vineyard tasks, can influence both yield and disease pressure. With labor becoming increasingly scarce and prevalence of grapevine trunk diseases infections shortening the ideal pruning window, growers are considering exploring mechanization to reduce labor demands.

This project evaluated pruning strategies for three major cold-hardy cultivars: ‘Brianna’, ‘La Crescent’, and ‘Marquette’. Trials were conducted at grower sites, comparing cane pruning and spur pruning (ranging from 2- to 5-node spurs). Additionally, we assessed hand, mechanical, and mixed (mechanical with hand follow-up) pruning methods on ‘Frontenac Gris’. A Vineyard Mechanization Tour was also held to expose growers to scalable mechanization practices from more established viticulture regions with a roughly analogous climate.

Key findings include:

• Spur pruning to 3-, 4-, or 5-node spurs increased yields across all three cultivars compared to the standard 2-node method.
• Cane pruning results varied: ‘La Crescent’ underperformed, ‘Marquette’ performed well, and ‘Brianna’ showed signs of overcropping.
• Hand, mechanical, and mixed pruning methods produced similar yields and fruit quality, though mechanical pruning showed higher severity of black rot and phomopsis.
• Labor savings were substantial: switching from hand to mixed pruning saved $420–$560 per acre, and from mixed to full mechanical pruning saved an additional $88–$199 per acre.

Several growers reported plans to increase spur length based on these results. While there was strong interest in mechanical pruning, no new adoptions have occurred yet due to the high initial investment.

1. Quantify fruitfulness of nodes of recently introduced cold-hardy grape cultivars at locations along canes.
2. Develop pruning recommendations for recently introduced cold-hardy grape cultivars.
3. Evaluate potential for mechanically pruning cold-hardy grape cultivars on high wire cordon training systems.
4. Compare disease infection incidence between mechanically pruned and hand pruned vines.
5. Familiarize growers of cold-hardy grape cultivars with successful and scalable mechanical pruning options.