Newly found Asian citrus psyllids prompt quick action in Tulare

After finding six Asian citrus psyllids (ACP) on three Tulare County yellow sticky traps last month, California scientists and officials are encouraging farmers to aggressively monitor and treat their orchards to prevent the sad fate befalling citrus farmers in Florida, where the pest and a serious disease it spreads are running rampant.

The July ACP find prompted the California Department of Food and Agriculture to quarantine 178 square miles in the Porterville area, placing severe restrictions on the movement of local citrus nursery stock and citrus fruit outside the area. It also prompted several hundred farmers and pest control advisers to gather July 30 at the International Agri-Center in Tulare for an update on the threat.

Like a scene from the film “Scared Straight,” Ken Keck, former executive director of the Florida Department of Citrus and now director of the California Citrus Research Board, admonished the California farmers to learn from the Sunshine State’s mistakes.

“I feel like the ex-con in front of a room of 17-year-olds,” Keck said. “All I can say is, ‘prevent, prevent, prevent.’”

Asian citrus psyllid is established in Southern California. Efforts in the southern part of the state are focused on managing the psyllids to reduce the likelihood they will find a tree infected with huanglongbing. Huanglongbing (HLB) is an incurable and fatal disease of citrus spread by ACP.

By working together and following science-based treatment strategies, UC Cooperative Extension specialist Beth Grafton-Cardwell believes farmers and CDFA can still eliminate ACP in the San Joaquin Valley, where the bulk of the state’s commercial citrus is grown.

At the Tulare meeting, Grafton-Cardwell explained the eradication strategy she developed by studying Asian citrus psyllid and huanglongbing disease management programs in Florida and Texas, another state where the pest is well established.

“We want to slow the spread of psyllid into new areas,” Grafton-Cardwell said. “We want to prevent psyllids from finding HLB infected trees.”

Although it is unlikely the pest and disease can be kept at bay indefinitely, Grafton-Cardwell said the battle will buy time for researchers to discover long-term approaches for maintaining California’s citrus industry in the presence of ACP and HLB.

Developing citrus varieties resistant to HLB through traditional breeding or genetic modification will take too long, she said. Scientists are considering such futuristic solutions as inserting HLB resistance into a mild form of the Tristeza virus and inoculating trees with the virus to fight HLB.

“Everyone is racing to come up with tactics to fight ACP and HLB,” she said. “I believe we will eventually be using multiple approaches, such as a repellent spray to keep ACP off the trees and perhaps breeding ACP that can’t transmit HLB and then flooding the population with these incapacitated psyllids.”

To fight ACP and HLB, growers and homeowners can access detailed information on the pest’s distribution, monitoring methods and treatment options on a new website created by Grafton-Cardwell with funding from UC Agriculture and Natural Resources.

For tap sampling, spray a plastic surface with soapy water and tap branch over surface.

The website advises farmers and homeowners to regularly conduct visual surveys and tap sampling (see video on right) in their orchards. “Yellow sticky card traps are not very attractive to psyllids,” it says.

If psyllids are found, immediate action is required.

Adult psyllids should be placed in a container with 90% alcohol and reported to the county agricultural commissioner’s office so the insect can be tested for HLB. Immature stages of the pest should be left on the tree so the ag commissioner’s office can make an official regulatory collection.

An ACP find should also trigger rapid and wide treatment with the most effective pesticides possible.

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