A Tough Shot Hole Borer Pest Impacting Northern San Diego County Avocados

A Tough Shot Hole Borer Pest Impacting Northern San Diego County Avocados

March 1, 2015

Traps Are Being Set up for Monitoring Polyphagous Shot Hole Borer

The California Avocado Commission continues to deploy traps and lures for polyphagous shot hole borer (PSHB) monitoring in the major avocado growing regions. The infestation is currently limited to Northern San Diego County, where thirteen groves have confirmed PSHB. Those groves have a total acreage of about 1,000 acres, but not all of the acreage is infested.

To date over 100 traps have been set-up in avocado groves in San Diego and Riverside Counties to monitor current infestation beetle levels and to serve as an early warning system should the beetle spread. In addition, traps with lures have been deployed in other avocado production areas to serve as sentinels. Ventura County now has 24 traps in place and another five are in San Luis Obispo County, and soon traps will be located in Santa Barbara County.

These traps are strategically placed in locations that have a higher susceptibility for the introduction of the PSHB, such as campgrounds, nurseries and green-waste facilities. There are also a few traps within avocado groves. Considering the high number of PSHB hosts, it is believed that movement of firewood and other plant materials from infested areas into non-infested areas presents the greatest risk. Most of the major handlers have set-up traps at their facilities as an additional safeguard.

Traps within the infested groves have shown some significant increases in beetle captures when the temperatures warmed. During January as UCR researchers monitored fifteen traps the average total number of beetles was around 100. In early February, though, when temperatures warmed those same fifteen traps had over 1,000 combined beetles in one day. This data is preliminary, but it suggests how rapidly the beetle activity may increase as summer temperatures begin to occur. Accordingly, it is imperative that growers who are located within a few miles of infested groves remain vigilant in their monitoring for PSHB, especially with spring and summer fast approaching.

Additional information regarding how to identify signs of PSHB may be found here: http://www.eskalenlab.ucr.edu/.

The Commission, prior to the start of harvest, worked with handlers to develop protocols for harvest and transportation practices to mitigate possible risk of PSHB spread, and these protocols may be viewed here: http://www.californiaavocadogrowers.com/sites/default/files/documents/PSHB-Harvest-Protocols-Fact-Sheet.pdf

Finally, a grower meeting has been scheduled for March 24th, 2015, from 9-11 am in Escondido. UC Riverside researchers and Commission staff will provide an update on field trials evaluating possible curative and/or prophylactic pesticides and fungicides. The meeting will be held at the California Center for the Arts, 340 North Escondido Boulevard, Escondido, CA 92025.

Tom Bellamore, President
Ken Melban, Director Issues Management
Tim Spann, Research Program Director