What To Do
The Humboldt County Agricultural Commissioner’s Office is asking residents who bought a vine at Costco on or after April 21 to contact the office at (707) 441-5260 or email AGCommissioner@co.humboldt.ca.us.
Residents are asked not to plant the vines, if they have not already, and not to “move or throw away the plants,” but to “place two garbage bags over the plant, secure them tightly and immediately contact” the office “for further guidance and to schedule an inspection.”
“The glassy-winged sharpshooter poses a serious threat and it’s important that we move quickly to prevent it from spreading,” Humboldt County Agricultural Commissioner Weylan Shaw said.
When the Humboldt County Department of Agriculture put out a call for assistance to help recover grape vines potentially harboring an invasive insect never before detected in the area, the community responded.
The result of a Fresno-based nursery breaching protocol meant to prevent the pest’s expansion, a total of 60 plants with glassy-winged sharpshooters possibly hitching a ride were sent to the Costco in Eureka between April 21 and May 21.
The same scenario played out in other stores across a dozen northern state counties. When the situation came to light, state and county ag offices went on the offensive to stop the non-native insect from spreading its wings.
Like little vampires, glassy-winged sharpshooters — also known as GWSS — feed on the fluids of plants, which in and of itself is not the problem, according to the University of California Statewide Integrated Pest Management Program. It’s a plant pathogen that transfers during the process that causes issues, including Pierce’s disease, which can devastate vineyards.
In an email to the Journal, Humboldt Supervising Agricultural/Weights and Measures Inspector Patrick Hoffman explains that “due to its larger size,” which he describes as about twice the size of its local counterparts, “it can vector the bacterium Xylella fastidiosa more effectively and to a wider host range.”
“X. fastidiosa is found in many parts of the world, including California,” he says. “It is known to infect about 600 plant species, most without symptoms, with different strains affecting different plants. Pierce’s disease of grape, citrus variegated chlorosis, and olive leaf scorch are economically important diseases due to symptom severity and crop value.”
According to the USDA Agricultural Research Service, Pierce’s disease alone costs California’s grape industry about $104 million per year.
After receiving notice here in Humboldt, Hoffman says inspectors set out to Costco.
“The first plant inspected had a GWSS egg mass,” he says. “To err on the side of caution, all grape plants remaining at Costco were double bagged in thick plastic trash bags and placed in a closed top dumpster for disposal. All other plants at Costco (non-grapes) were pulled from the sales floor and closely inspected. When no signs of GWSS were observed, these plants were returned to the sales floor.”
By then, according to Hoffman, 34 of the vines had already been sold. After putting out a public notice, as of Monday, 26 have been accounted for in locations stretching from Willow Creek to the Benbow area but mainly centered around Eureka and McKinleyville. Hoffman says, “none of the recovered grapes were at or adjacent to vineyards.”
In four cases, the vines were left in place after a close inspection showed no signs of an egg mass or the insect in question, he says.
“The remaining 22 plants were destroyed after egg masses were discovered, questionable early stage nymphs were observed, or by the owner’s request,” he says, adding the office is “continuing to receive contact from customers who purchased grapes from Costco and continue to visit properties and inspect for the presence of glassy-winged sharpshooter (GWSS).”
Costco is offering a full refund and is aiding in tracking down plants that may be carriers, according to state officials.
Containment efforts underway include sticky traps being placed inside and outside Costco and by “the homes of all customers who purchased grapevines from Costco, whether those vines were destroyed or not,” he says.
Even though the glassy-winged sharpshooter has never been detected locally before, Hoffman says Humboldt, like most counties in California, always has an eye out for the pest, with 117 monitoring traps in place “on potential host trees from spring through early fall as part of the Pierce’s Disease Control Program.”
Originally hailing from the southeastern United States and Mexico, the insect was first discovered in the state in the 1990s. Six entire counties, including San Diego, Los Angeles and Ventura, are now categorized as infested areas and portions of others, including Fresno, are also labeled as such.
With the glassy-winged sharpshooter preferring what Hoffman describes as areas having “warm to hot summers and mild winters,” Humboldt generally doesn’t really fit the bill and “and may temper its establishment.”
But, he notes, were Humboldt to be classified as a “generally infested” county, the designation “would impact nurseries and producers that ship outside of the county.”
“These producers could lose access to certain markets unless they meet specific Pierce’s Disease compliance requirements, which could significantly raise their cost of doing business,” Hoffman says.
Kimberly Wear (she/her) is the assistant editor at the Journal. Reach her at (707) 442-1400 ext. 105 or kim@northcoastjournal.com.
This article appears in Duane Flatmo Wants to Wow.
