May 31, 2023
Napa County, Calif. is well known for its pest exclusion efforts. It was through a focused effort several years ago that the European grapevine moth was eradicated after significantly impacting vineyards there.
The county’s annual crop report highlights the Napa County Winegrape Pest and Disease Control District’s 20th year, and the work it does to address threats from invasive insects.
In late 2001 the county agricultural department and wine grape industry worked with the California Department of Food and Agriculture to address glassy-winged sharpshooter (GWSS) issues starting to be seen across the state. The sharpshooter spreads a deadly disease in grape vines.
Since then, the county enhanced its GWSS detection activities beyond what the CDFA would fund through a voluntary grower assessment. Growers in the district later voted to expand the pest control district’s efforts to include other pests, including the vine mealybug.
The county’s efforts have since expanded to inform growers and residents of the impacts the spotted lanternfly poses to the wine grape industry and landscaping, should it make its way to Napa from the eastern United States.
According to the Napa County Department of Agriculture, the spotted lanternfly has a voracious appetite for plant sap. This can severely damage plants by draining their fluids. The pest is known to feed on the tree-of-heaven (Ailanthus altissima). The tree is an invasive species from Asia that is well-established in Napa County, including areas surrounding vineyards.
Napa County is said to have 31 detection traps in place on tree-of-heaven trees in a variety of locations, including near vineyards and along travel routes. Public education efforts continue to help growers, agricultural workers, and residents know what to look for and how to report the spotted lanternfly, should it find its way to Napa County.
Red Imported Fire Ant
Napa County apparently had a close call last December with the red imported fire ant, a native of South America that has established colonies across much of the southern United States.
According to the ag commissioner’s office, a homeowner apparently imported the fire ant in a potted plant brought with them when they relocated from the southern US. The fire ant infestation was reported to the ag commissioner’s office and the potted plant was confiscated and destroyed.
County Agricultural Commissioner Tracy Cleveland reported in her annual crop and livestock report that the homeowner’s property was inspected and surveyed for additional fire No fire ants were reported during that survey.
Cleveland said in her report that additional surveys and trapping will take place through the end of this summer to ensure the fire ant is not there.
The county continues to service over 7,000 other insect traps, looking for signs of various invasive pests, including the European grapevine moth, Asian citrus psyllid, Mediterranean fruit fly, Oriental fruit fly and the vine mealybug.
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