Monitoring Nurseries Key to Preventing the Spread of GWSS
Nursery stock is a high-risk commodity for spreading the glassy-winged sharpshooter (GWSS). Approximately 53 percent of California’s 13,000 licensed nurseries are located in GWSS-infested counties. Many of these nurseries ship to the non-infested areas of the state.
Plants at a Southern California nursery being inspected by a county ag inspector for GWSS egg masses before being shipped.
The CDFA’s Pierce’s Disease Control Program coordinates county activities throughout the state to mitigate the risk of moving the GWSS on nursery stock. These activities include:
1. Inspection of nursery stock in infested areas prior to shipping to non-infested areas 2. Treatment of nursery stock when necessary 3. Certification of shipments 4. Inspection of nursery stock at receiving nurseries prior to sale 5. Trapping in and near nurseries in infested and non-infested areas.
In 2017, there were 36,700 shipments of nursery stock from infested areas to non-infested areas. Viable life stages of GWSS were discovered at destination in only six of these shipments. Origin county inspectors stopped 108 egg masses, nine nymphs, and six adult GWSS from moving in nursery stock shipments.
Nursery Regulatory Program Update
From January 1, 2018 through March 31, 2018, there were 8,546 nursery stock shipments from the GWSS generally-infested areas to non-infested areas of the state. Shipments were down by approximately 649 compared to the first three months of 2017. No regulatory actions have needed to be taken so far this year.
During outgoing inspections from January through March 31, 2018, origin county inspectors stopped 14 egg masses from moving in nursery stock shipments.
Plants being sprayed as part of the ATP program prior to shipment to a non-infested area.
Nursery Stock Approved Treatment Program (ATP)
From January 1, 2018 through March 31, 2018, there were 3,235 ATP shipments consisting of 892,656 plants. The number of ATP shipments and plants for the same time frame in 2017 were 2,847 and 991,437, respectively. No regulatory actions have been necessary this year.