A new, $5.25 million greenhouse is being built on the University of California, Davis, campus to safeguard an important grapevine collection from red blotch disease and other pathogens.  

The 14,400-square-foot greenhouse will have a vestibuled entry, be insect-proof and provide another level of disease protection. It is being spearheaded by Foundation Plant Services, or FPS, which provides the U.S. grape industry with high-quality, virus-tested grapevine plant material. 

The 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, which provides the majority of grapevines planted in the United States. For the grape industry, it is essential to protect this material from disease-carrying insects and guarantee fast access to clean plant material.

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

A history of serving the grapevine industry 

FPS has maintained healthy grapevine planting stock on the UC Davis campus for more than 70 years in open fields at the Classic and Russell Ranch foundation vineyards. FPS scientists first detected grapevine red blotch virus at Russell Ranch in 2017. By 2021, an estimated 51.6% of the crop there was infected. Material from that vineyard is not being sold, and the site is now part of an epidemiological study to try to pinpoint how the disease is transmitted. 

FPS pathologists have detected red blotch on less than 1% of the Classic vineyard crop. But it may not always be that way in the future. 

“We don’t know how long the Classic vineyard will remain clean,” Al Rwahnih said. “Every testing season, this is what keeps me up at night. We’re not sure why it’s happening in Russell Ranch and not the Classic vineyard.” 

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

Two greenhouses part of plan

Normally the foundation has 4,000 vines available, but the greenhouse will only house 2,000 vines, so inventory will be cut in half. 

“This phase is just a starting phase,” Al Rwahnih said. “It’s not sufficient for our needs.”

FPS plans to build another greenhouse in the next two to three years to increase capacity.  

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

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

The first greenhouse is expected to be finished by the end of 2023. 

Funding for the first greenhouse is coming from a variety of sources. The California Fruit Tree, Nut Tree and Grapevine Improvement Advisory Board, managed by the California Department of Food and Agriculture, contributed $4 million to the project. The California Grape Rootstock Research Foundation gave $500,000, Foundation Plant Services with UC Davis is funding $450,000, and the California Grape Rootstock Commission gave $100,000.

“This is crucial for the grapevine industry, and we are very grateful for the support,” Al Rwahnih said.