Terminology note: cultivar or variety are used in viticulture
If you do not have records of the plant material planted in your vineyards, there two ways to determine the cultivar and rootstock. However, the methods have different levels of accuracy.
- Ampelography – You can use physical characteristics of the shoot tips, leaves, and fruit to identify the grape cultivar. The Vitis International Variety Catalogue can be used to search cultivars and rootstocks for images of shoot tips, leaves and fruit. Use the database search feature. This is helpful in determining the variety but is not completely definitive.
- DNA testing -- If you want to be certain about the cultivar or rootstock identification, send leaf samples for DNA testing at Foundation Plant Services. The service comes at a significant cost, but is the only way to specifically determine the cultivar. However, be aware that DNA testing cannot identify a cultivar to the clone level at this time. For rootstocks, you will need to use leaf tissue from suckers growing from below the graft union for identification.
Hobby grape growers/home garden
If you have a few grapevines in your home garden/landscape and need identification, you can use the resources listed above for commercial growers. However, it is often difficult to know which cultivars to begin searching for in online databases. Below are resources to help you determine which cultivars you may have in your garden based on common grapes sold to homeowners.
- Many grapes for the home garden are American grape varieties, largely because they are more disease resistant. These may be used for table grapes (fresh eating), juice (or wine), or jams/jellies. Some are interspecific crosses between American Vitis and Vitis vinifera. To learn more about different wine, juice and table grape varieties, check out the following online resources for descriptions and photos:
- Contact your local county Extension office for assistance. Specifically inquire with the Master Gardener Help Desk, as they may be able to further assist in cultivar identification based on their experience and other local resources. Keep in mind that there are thousands of grapevine cultivars grown worldwide, and it is difficult to positively identify the cultivar visually. Also, having diseased or unhealthy plant tissue makes it difficult for visual identification.