Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
University of California
Division of Agriculture and Natural Resources

UC blogs

Weather radar helps researchers track bird flu

This NEXRAD map shows where migrating waterfowl are gathered in rice fields, herbaceous wetlands and other agricultural land.

The same weather radar technology used to predict rain is now giving UC researchers the ability to track wild birds that could carry the avian influenza virus. Avian influenza, which kills chickens, turkeys and other birds, can take a significant economic toll on the poultry industry. In 2014- 2015, the United States experienced its worst bird flu outbreak in history, resulting in more than 48 million birds dying in 15 states, including California. 

“We use the existing network of weather radar stations in the U.S. in the same way that radar is used to track rain, except that we process the data to allow us to interpret the radar signal bouncing off birds instead of raindrops,” said Maurice Pitesky, UC Cooperative Extension poultry specialist. “The data can be interpreted to track birds.” 

Migrating waterfowl, such as Canada geese and common egret, could carry the avian influenza virus.
NEXRAD, or next-generation radar, is a network of 160 high-resolution S-band Doppler weather radars operated by the National Weather Service. The technology works best for tracking birds in the winter during feeding. When waterfowl leave their roosting locations in concert to feed, their bodies produce reflectivity of the radar beam.

“By tracking mass bird movements remotely in real-time, we hope to gain novel strategic insights with respect to surveillance and prevention of avian influenza transmission to domestic poultry,” said Todd Kelman, a veterinarian and engineer who co-leads the project with Pitesky, who is also in the School of Veterinary Medicine at UC Davis. They are exploring how the information might be used to prevent an outbreak.

In California, waterfowl migrate by the millions from September through March via the Pacific Flyway, where they winter in wetlands, rice and corn fields. The Central Valley alone is home to 3 million waterfowl at the height of migration.

“Using NEXRAD and various other approaches, we hope to be able to produce monthly or quarterly maps that will alert poultry producers as to the locations of waterfowl in the Central Valley of California,” Pitesky said. 

This Landsat map shows wetland coverage in the Sacramento Valley in 2007, a rainy year, and 2015, a dry year.

“Waterfowl populations can have different habitat based on the amount of precipitation in a given year,” said Pitesky. “Therefore, we need to use these types of monitoring tools to understand where waterfowl are located. Landsat, or satellite-based land imagery, and NEXRAD are two remote tools that may be very useful, as opposed to flyovers and banding, which are more expensive and not practical for large geographical areas.” 

The project — funded by UC Agriculture and Natural Resources — is a collaboration between UC Davis School of Veterinary Medicine and Jeff Buler, University of Delaware wildlife ecologist whose team first developed the NEXRAD approach in the Central Valley of California. They are also working with the U.S. Geological Survey, the California Department of Food and Agriculture, the California Poultry Federation, the Pacific Egg and Poultry Association and Point Blue, an organization that focuses on conservation science.

Posted on Wednesday, December 7, 2016 at 11:37 AM

Wild horse over-population is causing environmental damage

Most Americans envision healthy mustangs galloping free on the range when they think about the country's wild horse population. But UC Cooperative Extension rangeland advisor Laura Snell sees another image.

Wild horses are beautiful, but present land management challenges.

In conducting research on the over-populated wild horse territory at Devil's Garden Plateau in Modoc County, she witnesses a group of horses visiting a dwindling and damaged pond.

“Maybe there is enough for the lead stallion and the lead mare to drink. The rest stand there and look longingly at the diminished water source,” Snell said. “They do not seem content.”

The research Snell has underway at Devil's Garden was chronicled in the current issue of California Agriculture journal by executive editor Jim Downing. The federal government has determined the ideal horse population on the 230,000 acres of wild horse territory is no more than 402, however, more than 2,000 wild horses are running on the land.

Snell began working in the remote northeast corner of California in 2015.

“I had Modoc County ranchers coming up to me on my second day of work asking me how to solve the wild horse issue,” she said.

She realized that agencies and authorities responsible for policies that determine the horses' fate, and advocates who lobby strongly that the horses should be cared for humanely, don't see the poor conditions suffered by the horses and the environmental degradation of the land.

“The area is a quarter million acres in size. There are no main roads, so you have to take ATVs to see the horses,” Snell said. “We realized we needed to provide visuals to show people the horses and what the landscape looks like due to unmanaged grazing by the wild horses.”

Snell places wildlife cameras for two-week periods near 24 remote water sources in wild horse territory in Modoc and Lassen counties. At each site, the camera takes a burst of three pictures automatically every 15 minutes; motion detectors on the cameras also trigger a shot whenever an animal enters the field of view.

Laura Snell, left, and USFS rangeland management specialist Jenny Jayo mount a wildlife monitoring camera at Bottle Springs, a water source in Modoc National Forest. (Photo: Will Sukow)

Preliminary data from 2015 show some striking findings. At one spring site, for instance, more than 71 percent of all animals detected over the sampling period were horses. Cattle accounted for 19 percent and the rest were pronghorn antelope, deer and hawks. The study will continue through 2017.

Wild horses are running in the Devil's Garden territory, and outside the territory, on private and tribal land. Fences don't hold the horses in, Snell said. Federal wild horse management areas are intended for multiple uses, including livestock grazing, hunting, and wildlife habitat. But in Devil's Garden, livestock have been excluded because of the environmental degradation.

“It was never intended to be single use area,” Snell said. “The horses are gorgeous animals, but I also like to see pronghorn, elk and mule deer. Some groups of wild horses are getting large and studs are getting aggressive. I know people who no longer ride their personal horses because it's not really safe with the territorial nature of the stallions.”

The images and data from Snell's research are designed to inform management and policy decisions in hopes of easing the expensive and environmentally harmful wild horse over-population. Already U.S. Representative Doug LaMalfa (R-Oroville) has brought the study to the House Committee on Natural Resources and preliminary results have been shared with Bureau of Land Management's Wild Horse and Burro Advisory Board.

Wild horse impacts near Bottle Springs in the Modoc National Forest. (Photo: Will Sukow)
Posted on Tuesday, December 6, 2016 at 1:18 PM

Is 'palmageddon' coming to California?

Representatives from the date and ornamental palm industries, arborists and pest managers, parks and recreation officials, and home owners are uniting behind a University of California, Riverside initiative to slow the spread of the South American palm weevil, a palm tree-killing insect that has established in San Diego County.

“Everyone recognizes the threat and agrees it is significant,” said Mark Hoddle, UC Cooperative Extension specialist in biological control based at UC Riverside.

However, Hoddle said, action is hampered significantly by a lack of financial support at the state and federal level for research to answer questions about the distribution of the weevil in Southern California, how far it can fly from infestation zones, control options, and the most efficient and sensitive ways to monitor and trap it.

South American palm weevil.

Hoddle recently helped organize a symposium just outside San Diego on the South American palm weevil. Recent detection in California of the weevil, which has traditionally been found in South and Central America, the Caribbean and Mexico, has scientists, farmers and nursery industry officials worried because it threatens California's $70 million ornamental palm industry and $68 million commercial date industry.

“My personal feeling is we might be on the verge of a crisis now,” Hoddle said. “The big problem is we don't know how far the weevil has spread. We really need help from the public in tracking its spread.”

The South American palm weevil (Rhynchophorus palmarum) is not to be confused with the palm weevil Rhynchophorus vulneratus, which originated from Indonesia and was incorrectly identified as the red palm weevil, Rhynchophorus ferrugineus, when it was found killing palm trees in Laguna Beach in 2010. R. vulneratus was declared eradicated from California on Jan. 20, 2015.

Feeding by larvae of the South American palm weevil damage the growing area of the crown of palm trees. The tree is then unable to produce new fronds, and within months it dies. Canary Islands date palms are particularly vulnerable and it is likely date palms will be attacked too. California also has a native palm species (Washingtonia filifera), which grows in desert oases and may be vulnerable to attack.

Detection of the South American palm weevil was officially confirmed May 9, 2011. Seven additional detections were made in July and August 2011. These initial detections by the USDA were in San Ysidro in San Diego County, about two miles from the Mexican border. It is likely that the weevils flew from Tijuana, Mexico, where infestations and dead palms had been detected in December 2010.

UC Cooperative Extension specialist Mark Hoddle is monitoring palm trees at Sweetwater Regional County Park east of San Diego for South American palm weevil.

As a result of those detections, weevil traps were set up throughout California, Arizona and Texas with financial support from the USDA. A total of 111 South American palm weevils were captured in California; 109 in San Diego County and two in Imperial County. They were also found in Alamo, Texas, and Yuma, Ariz.

The traps were monitored from 2011 to 2013. Then, monitoring stopped when federal funding for the program expired.

Since monitoring stopped, it appears the problem has worsened, said Hoddle, who is also director of UC Riverside's Center for Invasive Species Research. In May 2016 he did a casual eight-hour driving survey in Tijuana, Mexico and found about 125 dead Canary Islands date palms that had been killed by the South American palm weevil.

In August, 2016, Hoddle placed 10 weevil traps at Sweetwater Regional County Park, about 15 miles east of San Diego. Since then, he has been catching about five to seven weevils per trap per month. In the coming months, he plans to start monitoring the heath of the palm trees in Sweetwater Regional Park using a drone.

Hoddle considers the South American palm weevil situation more dire than what he encountered with Rhynchophorus vulneratus because he fears the South American palm weevil has spread further and it spreads the red ring nematode (Bursaphelenchus cocophilus), which also kills palm trees.

Red ring nematodes, which have not yet been detected in California, can enter palm trees through the damage South American palm weevils do to the trees. The nematodes can also enter the bodies of the weevils when they are larvae. Then, the larvae turn into adult weevils which are strong flyers and they can then spread the nematode to other palms when the feed or lay eggs on them.

Dead palm tree infected by South American palm weevil. (Photo: Mark Hoddle)

Posted on Tuesday, December 6, 2016 at 8:46 AM

Seven tips for enjoying holiday meals

Before you gobble down that Thanksgiving turkey and pumpkin pie, take a moment to maximize your enjoyment.

The University of California has experts on every topic imaginable, including food and the science of taste and sensory experience. Here are their pro tips on making the most of your holiday meal.

1. Slow down and pay attention

People get the most pleasure from their food when they take the time to savor it fully, said UC Davis sensory scientist Michael O'Mahony. Try having everyone at the table taste the same food and then describe all the sensations they get from it. Everyone can write them down and then share their lists with each other. The person who finds the most sensations wins.

UC pro tips you can use to enhance holiday meals.

2. Smell your food

Flavor comes from both smell and taste, but the brain makes it difficult to tell the difference. When you smell your food while eating it, the volatile molecules go up to the nose through a back passage and stimulate the smell receptors. That's one of the ways the brain knows there is food is in your mouth. But rather than triggering a smell sensation, it feels like a broadening of taste.

Here's an experiment to show how much smell contributes to flavor: Hold your nose while putting some food in your mouth. Concentrate on the taste sensations you are getting. As you swallow, release your nose and notice how the flavor expands. The experiment works best with foods that have a strong odor such as a wine, sweet fruit drinks or gravy.

“Every time you eat you experience an illusion,” O'Mahony said.


3. Add salt in a pinch

If your host happens to serve a cheap red wine that is high in tannins (bitter), here's a tip to make it taste better: Put a pinch of salt in your mouth, O'Mahony said.

“The salt suppresses the tannin,” O'Mahony said. “Taste it again and it will taste like a mature wine.”

4. Think beyond bitter, salty, sour, sweet and umami

Are there more than just five basic tastes?

“It depends what you mean by basic taste,” O'Mahony said. “No one has ever really defined it properly. So it is a bit silly to say there are five things when we haven't actually defined what we are talking about. Whatever definition we choose, we don't know how many there are. There are certainly lots of different tastes.”

Amina Harris, director of the UC Davis Honey and Pollination Center, convened a taste panel to help develop the honey flavor wheel with more than 100 flavor profiles from leather and lemon to cotton candy and even cat pee.

“In general, honey is called sweet, but it has a huge amount of flavors,” Harris said. “Cat pee,” she adds, “is real. It's very pungent.”

Tracy Kahn, a UC Agriculture and Natural Resources researcher, curates on of the world's largest collections of citrus varieties.

5. Try new things

There are more than 300 honey varieties available in the United States. Citrus has even more diversity.

Tracy Kahn curates UC Riverside's Citrus Variety Collection, one of the world's largest with more than 1,000 varieties of citrus and citrus relatives.

“We have ranges of colors, sizes and shapes,” Kahn said. “There are fruits that are red, blue, purple, orange and yellow. There are fruits as big as a person's head and as small as a green pea, and a tremendous amount of aromas.”

UC Riverside itself has developed more than 40 citrus varieties, including popular Tango mandarins, and is working to develop new varieties all the time, including ones resistant to citrus greening disease.

For young children, Kahn suggests Kishu mandarins, which are small, seedless, sweet and easy to peel.

6. Be bold

Try mixing in your time-honored traditions with something new.

Kahn suggests making an appetizer with Australian finger lime, a citrus relative that tastes like lime but looks like caviar.

“Specialty chefs are using this,” Kahn said. “You could serve it with cream cheese and smoked salmon on crackers.”

Yuzu looks like a yellow mandarin, but it's not sweet and has a strong aroma. Its acidic juice can be used in sauces such as ponzu, she said.

Kahn also likes to add citrus to water. She suggests using variegated pink-fleshed Eureka lemons, which have rinds that are green, pink and white.

“They look beautiful in water,” Kahn said.

If you're looking for an alternative adult beverage, try mead (honey wine), said Harris, whose center at the Robert Mondavi Institute for Wine and Food Science hosts courses in making the popular drink.

This Thanksgiving, Harris plans to make a walnut-cranberry tart with honey instead of corn syrup while her daughter will make samosas instead of mashed potatoes.

“It's fun to push the envelope,” Harris said. “Let's go play.”

7. Know your limits

The holiday spread can be filled with temptations. Enjoy, but choose wisely. Don't eat until it hurts. Remember, some of the dishes might taste even better the next day.

“There are always leftovers,” Harris said.

People enjoy their food more when they savor the flavor.
Posted on Tuesday, November 22, 2016 at 9:30 AM
  • Author: Alec Rosenberg

New life for tea in the San Joaquin Valley

Fifty-five years ago, Thomas J. Lipton Inc. funded a tea study at the UC Kearney Agricultural Research and Extension Center in Parlier, which is piquing the interest of scientists today. For 18 years, researchers pampered and coaxed 41 tea clones to determine whether tea plantations could be a lucrative alternative for San Joaquin Valley farmers.

Scientists of the time predicted a potential $25,000 economic value of future California tea plantings. Today, tea is a $3.8 billion business in the U.S. and UC Davis recently launched a Global Tea Initiative. Kearney submitted its yellowed research reports, correspondence and newspaper clippings about the long-ago tea research to the initiative's collection of research, teaching and outreach spanning agriculture, social sciences, health, culture and economics of all things tea.

A syrphid fly hovers over a blossom on a tea plant at the UC Kearney Agricultural Research and Extension Center.

That got the attention of UC Davis chemistry professor Jacquelyn Gervay-Hague, who is studying microbes in the soil where tea is grown and their potential impact on the health attributes of tea.

“I believe there is a microbial exchange that ends up in the cup,” she said.

When the Kearney tea research program was scrapped in 1981, a prescient researcher had a handful of the best tea clones planted in the landscape around buildings at Kearney, where they stand today as fall-blooming non-descript shrubs.

Hague, who with her students frequently travels overseas to sample soil on tea plantations, learned of the plants at Kearney and recognized the opportunity to conduct studies in California.

“It's really remarkable,” she said.

Jeff Dahlberg, left, and Jacquelyn Gervay-Hague stand in front of nine tea plants in a landscape border at Kearney.

Kearney director Jeff Dahlberg believes the renewed interest in the center's tea, growing awareness about the healthful properties of tea, and increasing enthusiasm for artisanal tea and locally grown food could turn tea into a lucrative specialty crop for small-scale San Joaquin Valley farmers.

“This may be something like blueberries,” he said. “Twenty years ago, people thought they couldn't be grown in California. But with research conducted here at Kearney, there is now a thriving blueberry industry in the San Joaquin Valley and on the coast.”

It was the same intention that prompted Dahlberg's predecessors to support the tea studies in the 1960s and 70s.

At that time, 41 clones were propagated in a lathe house at Kearney, and later planted in a half-acre field plot. In 1967, UC Cooperative Extension agronomy researcher Karl H. Ingebretsen told a newspaper reporter that the plants came from clones that survived a similar USDA trial in the 1880s.

A 1964 news clipping about the tea project at Kearney.

“Most of the imported plants were taken from some growing in South Carolina, where the Lipton company found them 10 years ago growing wild,” Ingebretsen said in 1967.

The Kearney superintendent at that time, Frank Coddington, said the scientists hoped successful experimentation would lead to varieties of tea suitable for mechanical harvest and the production of instant tea, a product that in those days was becoming more and more popular.

The tea clones at Kearney grew well and appeared healthy, the reports said. Tea plants tolerated California's dry climate and stood the heat when irrigated properly. Five of the 41 clones were reported to show “real promise,” but when the tea project was terminated in 1981, only a few plants representing two of the clones were saved as landscape shrubs. Nine plants now grow on the west side of a corrugated tin warehouse, and four in the shade of knobby flowering pear trees just south of the original building at the site.

Tea shrubs that are more than 35 years old grow next to a building at Kearney.

Gervay-Hague plans to build on the results from early Kearney research with 21st Century agricultural production tools.

“I won't repeat the work done in the 60s, but they didn't know about the microbiome or genetics back then,” she said. “UC Davis has 3D imaging capability, which I want to use to watch the plants change. I would like to do DNA testing.”

The UC Davis chemist is applying for grants to build a repository of plants that may become the foundation of commercial tea gardens in California.

Posted on Friday, November 18, 2016 at 8:24 AM

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