Glassy-Winged Sharpshooter Making a Comeback?

Tacy Callies California Corner, Pests

glassy-winged sharpshooter
Glassy-winged sharpshooter (Photo courtesy of University of California, Riverside)

The glassy-winged sharpshooter (GWSS) is a pest that made California headlines from the late 1980s until its suppression at the turn of the new century. Unfortunately, it made a fast comeback in 2020, probably due to unusually warm winter weather. A warm winter and spring caused populations in the southern San Joaquin Valley to surge.

Kern County traps showed a threefold increase from below 50,000 to more than 150,000 last year, according to the U.S. Department of Agriculture Animal and Plant Health Inspection Service’s Plant Protection and Quarantine.

A threefold increase of GWSS was seen in Tulare County last year, from around 10,000 to nearly 30,000. Fresno County, which had few findings in the past two decades, caught just over 200 in 2019, but officials trapped 1,800 in 2020.

The GWSS can spread the bacterium Xylella fastidiosa, which causes Pierce’s disease in grapes, an incurable disease. It destroyed over 50% of the vineyards in Temecula in just two years and threatened to do the same to vineyards across California.

Although best known for its damage to grapes, citrus is one of the pest’s favorite hosts. Control often requires treatments in citrus groves, especially those located near grapes. And because citrus trees are green in the winter, the GWSS readily overwinters in groves. That is why citrus is a primary target for the Pierce’s Disease Control Program.

Control materials for Asian citrus psyllid (ACP), the pest that vectors huanglongbing, are often different than those used to control GWSS. In addition, treatment generally comes at different times. Therefore, GWSS control may require a new program of insecticide applications and continued trapping to monitor for the pest.

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About the Author

Len Wilcox

Correspondent at Large for Citrus Industry Magazine and AgNet West

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