On the edge of the UC Davis campus sits a world-renowned facility charged with ensuring grapevines, strawberries, fruit and nut trees, sweet potatoes, olives, pistachio, and roses are tested for viruses and pathogens. 

Cuttings from those selections at Foundation Plant Services, or FPS, are sold to nurseries in California and across the country to be propagated into millions and millions of plants for use nationwide and internationally. Material from here is also the starting point for certification programs run by the California Department of Food and Agriculture for several crops. 

“FPS is the largest clean plant center in the nation and also globally,” Director Maher Al Rwahnih said. “We’re the leader around the world.”

FPS, which is part of the National Clean Plant Network, was founded in 1958 and today has 45 employees, seven greenhouses, three screenhouses, shade houses, 11,400 plants on site and dozens of acres of vineyards and orchards. Staff manage 1,010 grape cultivars, 2,200 fruit and nut trees and the largest public rose collection in the United States.

A new $5.25 million greenhouse opened in May 2024 to protect grapevine stock from red blotch virus and other viruses carried by insects. A second screenhouse with the same intent is on hold due to funding. 

Targeting pathogens

FPS targets viruses in new and old ways. Scientists graft plant tissue onto indicator plants for screening to see if a virus causes symptoms like leaf curling or yellowing. They can also detect pathogens at the molecular level. When plants are identified as virus infected, the tissue culture lab at FPS conducts virus elimination therapy, which excises uninfected tissue to grow new plants. 

“When I tell you the plants are certified it means that they are tested for some targeted pathogens, which are known to cause issues and problems for the growers,” Al Rwahnih said in the tissue culture lab, where tiny sprigs of grapevines and almonds were grown from clean cells. “When you find a plant is infected, it’s not the end of the world because we can clean it.”

Staff also work on DNA identification for FPS crops.  

FPS cuttings produce millions of plants

FPS is primarily a self-supporting program, responsible for securing its annual budget through revenue generation from sale of plant material, service fees, user fees on distributed material, and grant funding and industry research programs. A primary focus of the FPS program is providing clean, certified stock to nurseries that can be propagated and sold to growers.

“It’s really important to start with clean, certified material because one bad mother vine can essentially turn into, depending on the variety, anywhere between 200 and 400 grafted vines annually with potential issues,” said Dustin Hooper, the vice president of sales – table grapes at Sunridge Nurseries. “UC Davis is on another level, which it should be because California agriculture is on another level compared to the rest of the U.S.” 

Each cutting, sample or pot at FPS has a QR code attached to it that can be scanned for identification, origin and other information so plants aren’t mislabeled or mishandled—an important quality control measure considering the material will be multiplied many times over. One mother strawberry plant sold to a nursery can produce 2.5 million to 3 million fruiting plants within two to three years and between 20 and 50 million grape plants sold annually can be traced back to FPS, Al Rwahnih said. 

“We’re talking about a huge number of plant material that we distribute,” he said. 

Nurseries and growers are not required to get their plant material from FPS but those in a voluntary virus certification program turn to the UC Davis facility and a few others in the U.S. 

“Essentially, they’re kind of the source of truth for everything in our industry,” Sierra Gold Nurseries CEO Reid Robinson said. “We use them to basically guard the material and ensure it doesn’t get infected with some kind of disease that would be a problem that could potentially carry on to the rest of the industry. They provide that sort of elite level of protection for material that is really, really hard to replace.”