First "Clean" means that the vine does not carry disabling diseases at the time of planting. That means vines are free from viruses, fungal and bacterial pathogens that cannot be cured once the vine is infected. The fungal and bacterial pathogens can be controlled by growing the vines in the proper climate, using sterile nursery protocols, and taking preventative measures to keep them healthy. Sunridge Nursery is located in the Southern San Joaquin Valley, which has a dry desert climate conducive to growing without as much risk of these organisms infecting their grapevines. The virus issue is a bigger challenge, because the health of the stock material is critical to preventing the spread of a virus. That is why the best vine you can possibly plant is a California Certified vine with a pedigree that is traceable back to a known mother vine.
California Certification refers to a Clean Stock Program that was set up with the cooperation of nurseries, the California University system, the California Dept. of Food and Ag., (CDFA), and the grapevine industry.
This program has written rules, is administered by CDFA, and the site of all grapevine source mother vines and all program activities are at Foundation Plant Services, (FPS), at U.C. Davis. The source vines are submitted to FPS, tested for at least two years, and once they are deemed "clean" two vines are planted in their Foundation Block. Nurseries are required to have CDFA do a site survey to gain site approval before acquiring the FPS foundation vines to start a Registered and Certified Increase Block. Only first generation cuttings from a nurseries' registered increase block can be called "Certified." Both the rootstock and the budwood must be sourced from a registered block to qualify as certified.
"Clean" is commitment that we have made to our customers and the industry. Sunridge Nurseries has replaced older increase blocks with the latest, most extensively tested material available, which FPS has dubbed as the "Protocol 2010" grapevine stock material. It has been shoot-tip cultured at FPS and verified that it is virus free and Crown Gall free using both RT-PCR and TaqMan qPCR methods to screen for viruses. FPS has also compared this material with original clones, to verify that they have not been altered during the treatments, before releasing them to nurseries.