Agricultural Commissioner / Sealer of Weights & Measure


Please check the CDFA web site for the most updated version of the GWSS host list.


(Information source: California Department of Food and Agriculture Web Site) Several counties notified the Department of Food and Agriculture that the hold exemption authorized by Food and Agricultural Code Section 6504 is waived for shipments of specific kinds of nursery stock. This action was taken to protect the counties' agricultural industry, particularly the grape industry, from the introduction of Homalodisca coagulata, the glassy-winged sharpshooter (GWSS), which is a vector of Xylella fastidiosa, the causal agent of Pierce's disease, from GWSS infested counties.


Alameda, Amador, Butte, Calaveras, Contra Costa, El Dorado, Fresno, Glenn, Imperial, Kings, Lake, Madera, Marin, Mariposa, Mendocino, Merced, Monterey, Napa, Sacramento, San Benito, San Joaquin, San Luis Obispo, San Mateo, Santa Clara, Santa Cruz, Shasta, Solano, Sonoma, Stanislaus, Sutter, Tehama, Tulare, Tuolumne, Yolo,Yuba and Santa Barbara.


"Host material" shall mean all nursery stock or food host plant as referenced in Appendix A. This does not include cut flowers or cut foliage.


GWSS has been detected in and apparently infests the counties of: Fresno, Kern, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, Tulare, and Ventura. Intrastate shipments found infested with this pest can be rejected under California Food and Agricultural Code Section 6521.

[Please note: Nursery stock from the infested states of Alabama, Arkansas, Florida, Louisiana, Mississippi, North Carolina, South Carolina, and Texas already enters California under a Quarantine Warning Hold Notice (008). GWSS is also known to occur in Mexico. Interstate shipments found infested with this pest can be rejected under California Food and Agricultural Code Section 6461.5. ]


California Nursery Stock Certificates shall not accompany shipments of host material shipped to an enforcing county. All shipments of host material from GWSS infested counties must be shipped under "blue tag" (or other mechanism which notifies the receiver of the hold requirement and notifies the destination agricultural commissioner of each shipment), and held for inspection at destination.


A nursery may elect to enter into a voluntary GWSS compliance agreement with its origin agricultural commissioner's office that outlines specific terms to prevent the spread of GWSS. The identification number for the participant is listed on their compliance agreement. The identification numbers must be assigned by the agricultural commissioner's representative when the compliance agreement is signed. To ensure that unique numbers are assigned to each participant, the identification number must begin with the origin county's two digit county number and be followed by a consecutive three digit number.

As an example, the fifth compliance agreement written in Los Angeles County would be assigned the identification number GWSS 19005.

Participating nurseries will be authorized to use a GWSS certification stamp on their shipping documents. Again, using the previous example, the stamp would have the following appearance:

  • GWSS
  • Compliance
  • GWSS 19005
  • Los Angeles
  • County


Some counties will allow nurseries in infested counties to ship using their nursery stock certificates if:

They are under written compliance agreement requiring adherence to specific protocols to ensure that shipped host nursery stock is free of GWSS;

Their shipping documents are marked with a GWSS certification stamp authorized by the origin county agricultural commissioner;

The shipping nursery notifies the destination county agricultural commissioner of the shipments in a timely manner. If the nursery stock has been treated with a pesticide prior to shipment, it is recommended that the notification include information regarding the pesticide used, date and time of treatment.

These counties are: Alameda, Amador, Calaveras,Contra Costa (24 hrs. advance notice required), Fresno, Glenn, Imperial, Marin, Sacramento, San Mateo, Santa Clara, Santa Cruz, Solano, and Tulare.