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Posts Tagged: exotic pests

California trees are suffering under climate change and invasive pests

Branch die-back in a Chinese flame tree because of invasive shothole borer infestation. (Photo: Beatriz Nobua-Behrmann)
Trees are facing stress from a variety of pressures in California, including climate change and exotic invasive pests, reported Jeanette Marantos in the Los Angeles Times

“There are lots of invasive pests everywhere because of global warming and the movement of plant materials in general,” said Philippe Rolshausen, UC Cooperative Extension subtropical tree specialist at UC Riverside.

Yellowing leaves, a thinning canopy and branch die-back are symptoms that the tree is sick. UC Master Gardeners, headquartered in UCCE county offices across the state, can provide free help, the article said.

Marantos listed possible reasons for common tree symptoms:

Yellow leaves: May be due to a lack of nutrients. A sudden jolt of fertilizer isn't the best solution. Homeowners often remove the best fertilizer and mulch for trees — their own fallen leaves.

Thinning canopies and branch die-back: May be the result of a soil-born disease, such a phytophthora, caused by excessive water. “Homeowners have a tendency to over-irrigate a tree that's not doing well, but soil-borne diseases actually thrive in wet soils, so that's making things even worse,” Rolshausen said. “Trees don't like standing water on their root systems because they can't breathe.”

Huanglongbing of citrus: Invested trees send up shoots of bright yellow leaves. Eventually, new leaves get twisted and mottled and the fruit stops ripening. The disease was first spotted in Southern California in the late 1990s and has since been detected in Los Angeles, Orange, San Bernardino and Riverside counties, according to a map prepared by University of California Agriculture and Natural Resources.

The Times article also recommended the UC Integrated Pest Management Program website to learn how to diagnose and control tree insects and diseases.

Posted on Monday, March 2, 2020 at 8:59 AM
Focus Area Tags: Yard & Garden

Protect the environment by leaving firewood at home

Firewood can harbor insects and diseases that threaten California wildlands. Leave it at home.
Memorial Day weekend, traditionally considered the beginning of California's camping season, is right around the corner. If you are preparing for an upcoming trip, you can help protect California's forests by buying firewood from a local source near the campsite rather than bringing it with you.

When people move wood from place to place, they may also be moving invasive insects and diseases that threaten California's landscape and wildland trees. The goldspotted oak borer, which is devastating native oaks in San Diego, likely hitchhiked from Arizona in firewood. The polyphagous shothole borer, walnut twig beetle and thousand cankers disease, and the pathogen causing sudden oak disease, all continue to spread to new areas on infested wood chips, plant debris or wood moved for woodworking or firewood.

Over the past year, the California Firewood Task Force has asked the public to "buy it where you burn it" — that is, don't bring wood from home when you camp, do use wood from local sources, and leave leftover wood at the campsite for the next camper. Even if wood does not appear to have borer holes or other evidence of pests, don't assume that the wood is pest free. Be on the safe side and don't move it.

The California Forest Pest Council established the task force in 2011 to educate Californians about what they can do to prevent movement of invasive pests in wood. The task force developed a web site, put up billboards across California, sponsored children's activities at parks and fairs, encouraged campgrounds to sell only local firewood, gave presentations across the state, and developed best management practices, posters, and other information to engage the public.

For more information visit www.firewood.ca.gov/.

Posted on Tuesday, May 20, 2014 at 1:36 PM

USDA provides funds for California specialty crops research

The USDA issued a news release on Friday announcing $55 million in block grants to enhance the competitiveness of specialty crops around the country, with California receiving more than $17 million. Of the 64 California projects, 19 are led by researchers affiliated with UC Agriculture and Natural Resources.

A large share of funding - $1.4 million - goes to nine food-safety projects to be coordinated by UC’s Center for Produce Safety, according to an article in the Fresno Bee.

"Scientists and researchers with the University of California and industry groups are exploring everything from whether frogs and lizards are potential carriers of E.coli to whether dust from a cattle operation can carry E.coli into a vegetable field," wrote Bee reporter Robert Rodriguez.

The executive director of the Center for Produce Safety, Bonnie Fernandez, told Rodriguez the funding comes at a time of heightened awareness of food safety among consumers and farmers.

"There are simply a lot of unanswered gaps of knowledge on these issues," Fernandez was quoted. "We want to know where the pathogens came from, how it attaches to a product and how we can reduce the risk of that happening."

Management of exotic pests is another issue where USDA provided funding for UC research, according to the listing on USDA's website. For example, grants will support efforts to:

  • Release and evaluate four exotic olive fruit fly parasitoids in order to improve sustainable table and oil olive management

  • Test the area-wide application of mating disruption of vine mealybug in Napa County

  • Evaluate the efficacy of organic pesticides for Asian Citrus Psyllid control so science-based control recommendations can be made to organic citrus growers

  • Survey resistance ratios in olive fruit fly populations from California regions not sampled in a previous study

Funds were also made available to expand and improve the online specialty crop production information now available on UC's Fruit & Nut Research and Information Center website and call-in center.

In addition, the new funding will allow UC researchers to work with several school districts and their regional partners to expand their procurement of local seasonal fresh produce, enhance their ability to integrate a specialty crop nutritional curriculum by providing outreach and professional development to school personnel, and assess changes in food preferences and dietary behaviors of children in participating school.

Other UC projects receiving the funding will look into onion seed production, strawberries' ability to restore impaired insulin, steam injection for soil disinfestation, and mealy plum aphid and leaf-curl plum aphid control in prunes.

The UC Center for Produce Safety to receive substantial research funds from USDA.
The UC Center for Produce Safety to receive substantial research funds from USDA.

Posted on Monday, September 20, 2010 at 9:55 AM

UC academics raise Asian citrus psyllid awareness

Be prepared with a plan, warns UC Cooperative Extension farm advisor Craig Kallsen, for the very real possibility of an Asian Citrus Psyllid quarantine area in Kern County, according to an article he authored that was published in Western Farm Press yesterday.

If the pest appears in the San Joaquin Valley's southernmost county, farmers will face a distinct challenge. Most of the citrus fruit harvested in Kern County is shipped to other counties for packing. If the county were to be quarantined, farmers would have to make sure the fruit has been processed and cleaned well enough to eliminate all plant parts - including leaves, stems and debris - and all life stages of the Asian citrus psyllid before shipping to packing houses.

"(The fact) that much of Kern County’s fruit is packed outside the county may make compliance with quarantine regulations potentially more difficult for many growers and packers that produce fruit in Kern County," Kallsen wrote.

Meanwhile, an article by freelance writer Dan Bryant, published earlier this week in Western Farm Press, outlined how the citrus industry is gearing up for Huanglongbing, the devastating citrus disease that can be spread by Asian citrus psyllid (to date, the disease has not appeared in California.)

The story included advice from UC Riverside citrus entomologist Beth Grafton-Cardwell. She told the reporter the telltale, early signs of Huanglongbing are yellowing of newly-flushed citrus foliage.

If Huanglongbing arrives in California, it could be distributed rapidly by the Asian citrus psyllid through backyard plants before moving on to commercial citrus. In that case, nurseries will have to place nursery stock in screen houses to keep it from the Asian citrus psyllid. Some, she said, have already prepared structures.

Immature Asian citrus psyllids.
Immature Asian citrus psyllids.

Posted on Wednesday, October 7, 2009 at 8:10 AM

Another attentive dog averts disaster

A FedEx package filled with curry leaves and guavas arrived in Sacramento Wednesday infested with 100 Asian citrus psyllids, the Los Angeles Times reported today. In a scenario eerily similar to one that took place in Fresno two weeks ago, a trained dog alerted authorities to the package, the pests were trapped, analyzed at a lab and determined to be free of the bacteria that causes the citrus disease Huanglongbing (HLB).

The package destined for Fresno was mailed from India; the package in Sacramento came from Houston, Texas.

"We know that this has been going on but it is just now that we are getting a feeling for how bad it is as we get more federally funded dog teams out there," the article quoted Beth Grafton-Cardwell, a UC Riverside citrus entomologist based at the UC Lindcove Research and Extension Center in Exeter.

UC scientists are working with CDFA, USDA and the citrus industry to prevent establishment of Asian citrus psyllid in California. But the effort has been met with several recent setbacks. Their greatest fear is for the incurable HLB disease that the psyllid transmits.

Psyllids not infected with HLB were found in Imperial and San Diego counties early last year; this week isolated populations turned up Los Angeles and Orange county backyard citrus trees.

Grafton-Cardwell believes the pests' eventual spread through the state's citrus regions is inevitable.

"It's only a matter of time before the huanglongbing disease finds its way to California from Mexico or elsewhere," Grafton-Cardwell told LA Times reporter Jerry Hirsch.

White, waxy tubules are a tell-tale sign of Asian citrus psyllid.
White, waxy tubules are a tell-tale sign of Asian citrus psyllid.

Posted on Friday, August 28, 2009 at 12:00 PM

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