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Posts Tagged: huanglongbing

Dogs enlisted to sniff out disease in citrus trees

The Citrus Research Board is arranging to bring specially trained dogs to the UC Lindcove Research and Extension Center to test their ability to sniff out the devastating citrus disease huanglongbing, reported Bob Rodriguez in the Fresno Bee.

CRB president Gary Schulz is working with the USDA, which is training dogs in Florida to identify trees with huanglongbing soon after the trees are infected. HLB has ravaged Florida's citrus industry. In California, the disease has been found about 800 Southern California backyard trees, but officials have so far managed to keep it out of the state's commercial orchards.

"The USDA has invested million of dollars in detector dogs and they have proven to be a credible diagnostic tool for early detection and screening trees," Schulz said.

The USDA has trained dogs to detect huanglongbing disease in Florida. (Photo: USDA)

HLB is spread by Asian citrus psyllids. Psyllids can pick up the the disease from infected trees and spread it to other trees as they feed. Symptoms may not show up in the tree until a year or two after it is infected. PCR (polymerase chain reaction) is the only way to positively identify huanglongbing infection in citrus. The process requires testing of many leaves or branches from the tree and may return a false negative if the samples selected for testing aren't infected, but other parts of the tree are.

Schulz said the HLB-detection dogs will start their California work in the southern part of the state before traveling north.

Posted on Tuesday, September 18, 2018 at 11:34 AM
Focus Area Tags: Pest Management

Three old trees might save the citrus industry

Three citrus trees that produce inedible fruit at the UC Lindcove Research and Extension Center in Visalia may be a game-changer for the citrus industry, reported Ezra David Romero on Valley Public Radio.

The trees are thought to be resistant to huanglongbing, a severe disease of citrus that has devastated the Florida industry and could become a serious problem in California. The citrus-saving potential of the three 34-year-old trees was outlined in an article by UC Agriculture and Natural Resources writer Hazel White in the most recent issue of California Agriculture journal.

UC Riverside citrus breeder Mikeal Roose collected seed from the trees and will test seedlings as soon as they are large enough. 

"So what (breeders) have to do is cross this with some edible varieties and eventually create something that has the gene for resistance, but also the genes for good fruit," said Beth Grafton-Cardwell, Lindcove director and research entomologist.

Huanglongbing disease has cut citrus production in Florida by more than half. It's been found in residential citrus trees in Southern California, but hasn't reached the state's vast commercial orchards yet. Grafton-Cardwell said she expects the disease will arrive in 4 or 5 years.

Eremocitrus crosses at Lindcove REC are potentially promising in the pursuit of a genetic source of resistance to HLB. The fruit is golfball size and inedible.
Posted on Friday, February 24, 2017 at 1:35 PM

Citrus trees sprayed for Asian citrus psyllid in Highland

Beth Grafton-Cardwell.
Backyard citrus trees in Highland, Calif., were sprayed with a pesticide to kill Asian citrus psyllids, reported Jim Steinberg in the San Bernardino Sun. The invasive pests pose a threat because they can carry huanglongbing disease, which is incurable. The California Department of Food and Agriculture is treating trees that have ACP to keep the pest number in California low.

“What they are really doing is buying time until disease resistant trees become available, or there is some treatment for the (huanglongbing) disease,” said Matt Daugherty, a UC Cooperative Extension entomology specialist based at UC Riverside.

The reporter also spoke to Beth Grafton-Cardwell, who is a UCCE entomology specialist at UC Riverside and director of the UC Lindcove Research and Extension Center in Tulare County. She said that it is unlikely huanglongbing was completely wiped out in the Southern California areas where infected trees have been found, even though CDFA destroyed the infected trees.

A tree can be infected for a year before it shows symptoms, she said. 

Grafton-Cardwell asks homeowners to monitor backyard trees for signs of Asian citrus psyllid and report any finds to CDFA or their county agricultural commissioner's office. For more information, see the video below.

Posted on Tuesday, May 3, 2016 at 1:29 PM

Californians are checking new growth on citrus for Asian citrus psyllid

Beth Grafton-Cardwell speaks with ABC30 reporter Dale Yurong, left, and cameraman Sam Gill at the UC Lindcove Research and Extension Center.
The Asian citrus psyllid is public enemy No. 1 at the UC Lindcove Research and Extension Center in Exeter, reported Dale Yurong on ABC30 Action News in Fresno. Yurong visited Lindcove to interview UC Cooperative Extension citrus entomology specialist Beth Grafton-Cardwell, who along with other UC ANR experts is calling on Californians to join the fight against the pest.

"Basically, you just look really closely (at new growth) with any kind of magnifying device you have to see if you can find any insects on there," Grafton-Cardwell said.

If tiny yellow eggs, sesame seed-sized nymphs, or ACP adults are found, take action. Maps, treatment protocols and other information that detail what to do when ACP is present are available at

Since ACP can spread the devastating citrus disease huanglongbing (HLB), controlling the insect population will buy time for researchers working around the world to find a way to grow healthy and delicious citrus fruit in the presence of HLB.

Yurong reported that the disease has been found in a dozen Southern California trees. Grafton-Cardwell figures Valley trees will ultimately get infected.

Dale Yurong poses with a giant mock-up of Asian citrus psyllid.
"HLB is going to come. We fully expect it to come up here because it rides in the bodies of the psyllids," she said.

Reed Fujii of the Stockton Record interviewed Karey Windbiel-Rojas, a UCCE advisor for home and garden integrated pest management, for a story on Asian citrus pysllid.

“It's really important to detect Asian citrus psyllid in backyard trees because one psyllid can carry the disease from tree to tree in a residential landscape,” Windbiel-Rojas. “Citrus growers, they treat all their fields, but home gardeners don't necessarily treat or monitor their backyard trees so it can spread a lot faster in backyards than in managed citrus orchards.”

Stories about the call to check trees this spring for Asian citrus psyllid also appeared in:

View a four-minute video about Asian citrus psyllid here:

Posted on Wednesday, March 9, 2016 at 8:27 AM

New Asian citrus psyllid website helps farmers and homeowners connect the dots

The early morning agriculture show on KMJ 580 in Fresno opened this morning with comments about UC's new Asian citrus psyllid website from Beth Grafton-Cardwell, UC Cooperative Extension specialist in the Department of Entomology at UC Riverside.

"There are a lot of websites out there relating to Asian citrus psyllid and huanglongbing disease," Grafton-Cardwell said. "What I tried to do in this one is give it a management focus with action steps: Here's where the bug and disease are, here's what you should do if you're a grower, here's what you should do if you're a homeowner. It connects the dots."

The story notes that the website includes a cost estimator for growers and homeowners that was developed by Karen Jetter, economist with the UC Agricultural Issues Center. The estimator lists effective pesticides and calculates the costs of application.

"It's a good way to figure out how you can help control Asian citrus psyllid," Grafton-Cardwell said.

The new website is at

The new Asian citrus psyllid website can be found at
The new Asian citrus psyllid website can be found at

Posted on Wednesday, August 21, 2013 at 12:04 PM

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