The University of California, Davis, announced plans to build a new greenhouse to safeguard an important grapevine collection from red blotch disease and other pathogens. According to a news release, the greenhouse will help guarantee the grape industry continues to have fast access to clean plant material.

Construction of the 14,400-square-foot greenhouse is being led by Foundation Plant Services and is expected to be completed by the end of 2023.

According to the news release, the FPS program serves as the primary source for grapevine plant material distributed to nurseries under the California Department of Agriculture’s Grapevine Registration and Certification Program.

“The program is considered the largest quarantine center for the grapevine industry in the United States,” said plant pathologist and FPS director Maher Al Rwahnih, in the release. “This is kind of a game-changer for us.”

For more than 70 years, FPS has maintained healthy grapevine planting stock on the UC Davis campus in open fields at the Classic and Russell Ranch foundation vineyards. FPS scientists first detected grapevine red blotch virus at Russell Ranch in 2017, and an estimated 51.6 percent of the crop there was infected by 2021. FPS pathologists have detected red blotch on less than 1 percent of the Classic vineyard crop.

“We’re not sure why it’s happening in Russell Ranch and not the Classic vineyard,” Al Rwahnih said.

According to the release, material from the Russel Ranch vineyard is not being sold, and the site is now part of an epidemiological study to try to pinpoint how the disease is transmitted.

Once the new greenhouse is operating, grapevines propagated from plant material in the Classic vineyard will be moved into the greenhouse, tested and verified to be disease-free. From there the material will be sold to nurseries, which will grow additional plants to sell to growers.

Because the new greenhouse will have capacity for only 2,000 vines, half of the program’s normal inventory, construction of a second greenhouse is planned in the next two to three years.

“We have a large selection, and we need to make sure all the varieties that are important to industry are contained,” Al Rwahnih said.

Industry groups and FPS identified greenhouses as the best way to protect the plants from red blotch and other pathogens transmitted by insects. The same groups are also consulting on the grape varieties to include in the greenhouse.

Funding for the first greenhouse will be provided from a variety of sources, including the California Fruit Tree, Nut Tree and Grapevine Improvement Advisory Board, managed by the California Department of Food and Agriculture; the California Grape Rootstock Research Foundation; Foundation Plant Services with UC Davis; and the California Grape Rootstock Commission.

by Jonelle Mejica