University of California scientists began releasing a natural enemy of Asian citrus psyllid in Riverside today (Dec. 20) to help control an invasive pest that could be devastating for the state’s $1.1 billion citrus industry and citrus trees in residential landscapes.

Tamarixia radiata – tiny, stingless parasitic wasps that lay eggs in Asian citrus psyllid nymphs – were released in a citrus grove behind the residence of UC Riverside Chancellor Tim White. Over the next several years, UC Riverside and California Department of Food and Agriculture scientists will raise thousands of Tamarixia for release throughout California. The Tamarixia larvae will eat the ACP nymphs, killing them, and emerge as adults about 12 days later. Adult female Tamarixia also eat other ACP nymphs, killing many this way as well.

UC Cooperative Extension biological control specialist Mark Hoddle and his wife Christina Hoddle, an assistant specialist in entomology, collected colonies of Tamarixia radiata during four trips to the Punjab region of Pakistan during the past 18 months. In all, about 1,500 parasitic wasps were brought to Riverside from Pakistan under permit from USDA-Animal and Plant Health Inspection Service. Twelve colonies had been quarantined at UC Riverside.

On Dec. 7, 2011, state and federal authorities cleared Tamarixia from quarantine with the issuance of a permit to release this natural enemy for establishment in California. The parasitic wasps can’t bite or sting people or animals. Safety testing in quarantine has demonstrated that the parasites are disease free and pose no environmental risk.

The Indian subcontinent is likely part of the native range for Asian citrus psyllid, Hoddle said. The first study of the pest was published in 1927 by scientists in the region. Asian citrus psyllid is now found in parts of the Middle East, South and Central America, Mexico and the Caribbean. In the United States, this psyllid was first detected in Florida in 1998 and is now also found in Louisiana, Georgia, South Carolina, Texas and Arizona. In 2008, the pest was detected for the first time in California in San Diego and Imperial county backyard trees. Large populations of Asian citrus psyllid are now well established in urban areas of Los Angeles, San Bernardino and Riverside counties.

When Asian citrus psyllids feed on citrus leaves and stems, they damage the tree by injecting a toxin that causes leaves to twist and die.  More important, however, is the psyllid’s ability to spread a bacterium that causes Huanglongbing disease.  Huanglongbing, also known as citrus greening, is one of the most harmful diseases of citrus worldwide. The leaves on infected trees turn yellow, the fruit becomes bitter and eventually the tree dies. There is no known cure for citrus, and this plant disease is not a risk to people.

Huanglongbing has made its way to Mexico and Florida, but so far it has not been detected in California. Currently, the citrus industry is dependent on insecticide sprays to control ACP and prevent the introduction of Huanglongbing. UC Cooperative Extension citrus entomology specialist Beth Grafton-Cardwell, director of the UC Lindcove Research and Extension Center, welcomes the promise of biological control with introduced natural enemies.

“This is very good news for the integrated management of Asian citrus psyllid and a highly significant contribution of the University of California,” Grafton-Cardwell said. “Parasitoid releases will add a new and exciting component to the management program for ACP, especially for the many homeowners who have citrus trees in their yards.”

Hoddle said Tamarixia won’t eradicate Asian citrus psyllid, but scientists predict it will reduce the densities of the pest, giving other control practices a better chance of working. Commercial citrus producers in California will still need to apply insecticides to control Asian citrus psyllid and prevent the spread of Huanglongbing, should it be found in the state. However, the frequency of these applications may be reduced because Tamarixia is killing ACP nymphs in areas that are not sprayed.

Hoddle collected the parasites in collaboration with scientists in the Department of Agri-Entomology at the University of Agriculture in Faisalabad (UAF), Pakistan. UAF was an ideal base for the project, Hoddle said, because it had citrus research plots infested with Asian citrus psyllid that have not been treated with insecticides. The university is also situated near local commercial citrus production, the area has a climate similar to citrus-growing regions of California, and the university’s vice chancellor, Iqrar Khan, is a UC Riverside graduate who also has an active research program on Huanglongbing in Pakistan.

In March and April 2011, Hoddle spent four weeks at UAF to set up research plots in kinnow and sweet orange trees. Coincidentally, kinnow is a mandarin that was bred at UC Riverside in 1935 and accounts for 85 percent of citrus produced in the Punjab. Hoddle and his Pakistani colleagues collected 24 male and 56 female Tamarixia radiata, which were brought back to UC Riverside to establish colonies.

Hoddle returned from a June 2011 trip to Pakistan with 151 male and 255 female Tamarixia radiata. An October and November 2011 visit netted another 800 parasitic wasps.

“Gathering insects from citrus plants in the Punjab generated an immense amount of curiosity,” Hoddle said. “Kids in particular were super-curious about what we were doing, where we had come from and why we had come to Pakistan. The people in the Punjab were incredibly courteous, polite and generous.”

Hoddle has trained a Pakistani graduate student Shouket Zaman Khan at UAF to monitor the interaction of Asian citrus psyllid with its natural enemies in their native environment. The researchers will determine whether other natural enemies of the pest could provide additional biological control of California ACP in the future.

Funding for the Asian citrus psyllid biocontrol effort has been provided by the California Department of Agriculture Food and Agriculture Specialty Crops Program, the USDA Citrus Health Response Program, the Citrus Research Board, and the UC Hansen Trust.

Tamarixia radiata (female)	Tamarixia radiata (male)
Click here for high resolution.	Click here for high resolution.

 

MEDIA CONTACT: Mark Hoddle, UC Cooperative Extension biological control specialist based at UC Riverside, (951) 827-4714, mark.hoddle@ucr.edu

University of California scientists have for the first time achieved the same yields in cotton and tomato research plots managed under conservation tillage strategies as they did on adjacent plots using conventional tillage practices.

“The bar has been set,” said UC Cooperative Extension vegetable crops specialist Jeff Mitchell. “After toiling for more than a decade, we’ve finally succeeded in putting the pieces together this past season.”

Researchers harvested 3.4 bales per acre of cotton and 53 tons per acre of processing tomatoes using no-till techniques. Plots managed with conventional tillage practices averaged about 3.4 bales per acre for cotton and 49 tons per acre for tomatoes.

The research was conducted at the UC West Side Research and Extension Center near Five Points, Calif. Scientists established the cotton crop by direct seeding into beds that had not been touched since the preceding tomato crop, except by two herbicide sprays. The 2011 tomato crop was established with a no-till transplanter following the 2010 cotton crop, which had only been shredded and root-pulled under a waiver granted by CDFA’s Pink Bollworm Eradication Program.

The 2011 regime represented the first time since the start of the study in 1999 that the Five Points research team strictly followed no-tillage techniques for both crops. In past years, in which tomato yields reached the mid-60 tons per acre, in-season cultivation for weed control was used. In 2011, however, the goal of going completely no-till was realized in preparation for 2012, when the field will be converted to subsurface drip irrigation for all subsequent no-till plantings. Scientists believe the 2011 tomato harvest for both conventional and no-till plots was lower than in previous years because planting took place April 7 due to weather and scheduling delays.

UC Cooperative Extension agricultural economist Karen Klonsky estimates that switching to no-till production reduced expenditures by about $135 per acre for the tomato crop and about $40 per acre for cotton.

“What we’re trying to do in this research,” Mitchell said, “is to look far into the future and evaluate the true costs and benefits of these alternative systems. Producers, as well as the general public, can then better understand broad future benefits and goals for sustainable crop and resource management, allowing farmers to develop and eventually adopt production practices that might best reach these goals.”

Future goals for conservation tillage production systems include profitability, resource quality, conservation, as well as broader ecosystem services.

“No-till makes sense as a means for lowering production costs and cutting dust and greenhouse gas emissions,” Mitchell said. “No-till also improves soil functions, such as increased carbon storage, greater stability of soil aggregates, increased porosity and water infiltration, and a larger population of earthworms.”

The benefits of no-till farming have been recognized by researchers and farmers in other regions, such as the Great Plains and the Pacific Northwest regions of the U.S., across much of Canada, and also throughout large areas of South America.

“These benefits start to pile up pretty fast once longer-term and broader sustainability goals are factored in,” Mitchell said.

Mitchell and his Five Points team are part of California’s Conservation Agriculture Systems Institute (CASI), a diverse group of more than 1,500 farmers, industry representatives, university, Natural Resource Conservation Service and other public agency members. Over the past 10 years, the team has come together to develop information on the true costs and benefits of the production system and irrigation management alternatives and to help develop appropriate sustainability goals for the long haul. For more information on the body of CT research, see the UC Conservation Tillage website.

“One of the things that CASI does is track changes in tillage management practices that are used throughout the San Joaquin Valley,” said long-time member and former air quality coordinator for the California Association of Resource Conservation Districts Ron Harben. “Our most recent survey for 2010 showed an increase of about 5 percent in no-till and strip-till acreage over previous years. As of 2010, over 47 percent of the cropland in the San Joaquin Valley is using some form of conservation tillage.”

A University of California wildlife research team working in the Sierra Nevada is asking the public to donate clean, gently used socks for research on a rare weasel called the Pacific fisher.

The team is part of the Sierra Nevada Adaptive Management Project  (SNAMP), which is examining the effects of forest thinning, as currently done by the U.S. Forest Service, on the health of local wildlife, the forest and water resources. The U.S. Forest Service implements these thinning treatments out of concern for excessive fire risk.

But what kind of research could go through hundreds of socks a month? After years of experimentation, the research team has determined that socks are the ideal receptacle for hanging fisher bait in trees. The baited socks are hung in trees in view of motion-activated cameras. As the animal moves, climbing the tree and chewing on the sock, the camera takes photos that allow the scientists to identify the species.

The researchers are going through 250 pairs a month, at a considerable cost, to create the “chicken in a sock” bait stations to survey the distribution of Pacific fishers in a 500-square-mile area of forest near Bass Lake.

Besides the cost, Rick Sweitzer, UC Berkeley wildlife biologist and project leader. is spending time in the Wal-Mart checkout line with a cart full of socks when he could be doing research. The scientists don’t need new socks; they would prefer old, unmatched, non-holey ones,something everyone has cluttering up their sock drawers.

In an effort to reduce, reuse and recycle, the SNAMP wildlife research team is
putting out a call for lost and lonely socks. Socks may be delivered or mailed
to 40799 Elliott Dr., Oakhurst CA 93644.

The Pacific fisher is a small, nocturnal carnivore that perches and dens in large,
old-growth pine and oak trees. Once widespread across the high elevation
forests of the Sierra Nevada and in the coastal mountains of northwestern
California, fishers are now only found in two small isolated populations. One
group lives near the California-Oregon border. The others are in the southern
Sierra Nevada.

Data being collected by UC scientists about the movements, habitat preferences and
survival of fishers in the southern Sierra Nevada will be used to aid the
multiple agencies, academic institutions, environmental groups, and mountain
residents who are working together to ensure that long-term wildland management
promotes forest health, wildfire control and wildlife conservation.

For more information, contact Anne Lombardo at amlombardo@ucdavis.edu.
To read more about the research project visit the SNAMP website at http://snamp.cnr.berkeley.edu.

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EDITORS: A photo of a Pacific fisher grabbing a bait-filled
sock can be downloaded from http://ucanr.org/blogs/Green.

The UC Lindcove Research and Extension Center has a new, state-of-the-art fruit grader, which automatically gathers detailed information on individual citrus fruits for California researchers. The machine provides data that has not been available to Lindcove researchers before.

Typical fruit grading equipment determines fruit size, count and grade. The Compac InVision 5000c has three lighting systems – fluorescent, ultraviolet and near infrared – plus a weigh bridge that together measure fruit dimensions, weight, color, and blemishes from insect damage, scarring and sunburn. Without spoiling the fruit, the grader also determines its sweetness and assesses internal damage. The new line can handle citrus fruit sizes ranging from a small mandarin up to a grapefruit.

“This equipment will give our researchers much more precise information for making comparisons,” said Beth Grafton-Cardwell, director of the Lindcove REC. “Our old packing line could tell us an overall color of the fruit. The Compac grader precisely defines how much of the surface area is green, yellow and orange.”

Highly advanced software works in conjunction with the equipment, recording measurements and a series of photographs – color and ultraviolet – for each individual fruit, allowing scientists to run correlations between all the parameters.

“We can determine which rootstock and scion combinations give the perfect size, sweetest taste and best ripening fruit,” Grafton-Cardwell said. “We will be able to train the software to recognize various types of pest damage – such as damage from katydids and citrus peelminer – and demonstrate which pesticides best protect the fruit from damage.”

In the past, labor costs limited researchers to gathering such detailed information from only a small sample of fruit on certain trees. With the new Compac grader, all the fruit from particular trees can be thoroughly assessed.

Another benefit of the upgraded equipment is its light-touch. The machine can gather data about mandarin oranges without harming the delicate peel. Growing interest in mandarins has UC scientists devoting more time and resources to the diminutive fruit. While Valencia and navel orange acreage is holding steady or dropping in California, mandarin acreage has tripled in the last 10 years.

“As the Valencia market has declined, many Valencia orchards are being replaced with mandarins,” Grafton-Cardwell said. “We have dozens of excellent varieties of mandarins and consumers love them because they’re easy to peel. Mandarins are the wave of the future.”

The cost of the Compac fruit grader was covered by the Citrus Research Board, a grower-funded organization created to support citrus research.

“The new fruit grader is another example of the excellent collaborative relationship the University has with the citrus industry,” Grafton-Cardwell said.

See the components of the new fruit grading system in the video below: