Grapevine cultivar diversity is extraordinarily large. Whether we talk about wine, table, or raisin cultivars, as well as the rootstocks on which they are grafted, the diversity is remarkable—not only in fruit and enological characteristics but also in their performance in the field. Choosing the right cultivar and rootstock for a specific vineyard is a complex decision that requires a deep understanding of the plant materials, the vineyard’s terroir, and the market.

In VEN101A – Viticultural Practices, Dr. Diaz-Garcia teaches students about the vast grapevine diversity across the world. During the first weeks of the course, students learn ampelography, the study of grapevine identification, where they examine key characteristics of the vine—such as leaves, shoots, and clusters—to identify cultivars. Wine grape cultivars, including important clones relevant to California and other major wine-producing regions, are studied in detail. Midway through the course, students are tested on their ability to identify 15–20 cultivars in the vineyard. The course then progresses to the study of wild Vitis species and rootstocks, emphasizing the importance of selecting the appropriate rootstock to match the vineyard’s soil, climate, and production and quality goals. Topics such as grapevine breeding and the development of new disease-resistant varieties, including resistance to Powdery Mildew and Pierce’s Disease, are also discussed. 

To complement the course, students are offered the opportunity to visit Foundation Plant Services (FPS) at UC Davis and a major grapevine nursery in California. These visits provide firsthand insights into the processes of testing and certification, importation and regulation, and large-scale propagation of grapevines.