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Clearing habitat around crops fails to reduce pathogens

A farming landscape can be co-managed for both produce safety and nature conservation. Promising practices include buffering farm fields with non-crop vegetation to filter pathogens from runoff and planting low-risk crops between leafy green vegetables and grazeable lands.(Illustration by Mattias Lanas and Joseph Burg)
The effort to improve food safety by clearing wild vegetation surrounding crops is not helping, and in some cases may even backfire, according to a new study led by researchers at the University of California, Berkeley.

The findings, reported today (Aug. 10), in the journal Proceedings of the National Academy of Sciences, call into question the effectiveness of removing non-crop vegetation as a way to reduce field contamination of fresh produce by disease-causing pathogens. This practice led to extensive loss of habitat in a region that is globally important for food production and natural resources.

The practice was implemented largely in response to a 2006 outbreak of pathogenic E. coli in packaged spinach that killed three people and sickened hundreds of others in the United States. That outbreak was traced to a farm in California's Central Coast, a region that supplies more than 70 percent of the country's salad vegetables. The disease-causing E. coli strain was found throughout the farm environment —  including in the feces of nearby cattle and wild pigs — but the cause of the outbreak has never been officially determined.

"Wildlife took much of the blame for that outbreak, even though rates of E. coli in wildlife are generally very low," said study lead author Daniel Karp, a NatureNet postdoctoral research fellow in UC Berkeley's Department of Environmental Science, Policy and Management and The Nature Conservancy. "Now, growers are pressured by buyers to implement practices meant to discourage wildlife from approaching fields of produce. This includes clearing bushes, plants and trees that might serve as habitat or food sources for wild animals. Our study found that this practice has not led to the reductions in E. coli and Salmonella that people were hoping for."

Instead, the study authors noted that the presence of diverse habitats bordering food crops can actually provide a number of agricultural benefits.

"There is strong evidence that natural habitats surrounding crop fields encourage wild bee populations and help the production of pollinated food crops," said study senior author Claire Kremen, a UC Berkeley professor of environmental science, policy and management. "There have also been studies that suggest that a landscape with diverse plant life can filter out agrichemical runoff and even bacteria. Changing this dynamic shouldn't be taken lightly."

‘No reason to continue' habitat removal

The researchers analyzed about 250,000 tests of produce, irrigation waters and rodents conducted by industry and academics from 2007 through 2013. The tests were conducted on samples from 295 farms in the United States, Mexico and Chile, and targeted the presence of pathogenic E. coli, Salmonella and generic strains of E. coli. The researchers combined the test data with a fine-scale land-use map to identify characteristics of the landscape surrounding the agricultural fields. 

The researchers found that the removal of riparian or other vegetation did not result in lower detection of pathogens in produce, water or rodents. Overall, the prevalence of pathogenic E. coli in leafy green vegetables had increased since the outbreak, even as growers removed non-crop flora. In fact, the growers who removed the most vegetation experienced the greatest increase in pathogenic E. coli and Salmonella in their vegetables over time. 

"Clearing surrounding vegetation is a costly, labor-intensive practice that threatens wildlife habitat," said Karp. "Since it does not improve food safety, there is no reason to continue this practice." 

The study did find, however, that the likelihood of detecting pathogenic E. coli was greater when fields were within 1.5 kilometers of grazeable land than when they were farther away.

"It is unclear whether it was the cattle or wildlife grazing on those lands that were responsible for the elevated pathogen levels, but there are a number of ways that farming and ranching can co-exist in a diversified system," said Karp.  

Some suggestions include:

Leaving strips of vegetation between the grazed areas and fresh produce areas

Fencing off upstream waterways from cattle to prevent waste from going downstream

Planting crops that are usually cooked before being eaten – such as corn, artichokes and wheat – between fresh produce fields and grazeable lands

Reforming farming practices

After the 2006 E. coli outbreak in spinach, California's agricultural industry implemented a voluntary certification program called the Leafy Green Products Handler Marketing Agreement. At the federal level, in 2011 President Obama signed the Food Safety Modernization Act, considered one of the most sweeping reforms in farming practices in decades. Both efforts shift the focus to preventing rather than responding to outbreaks.

Notably, neither the federal law nor the state program calls for the removal of wildlife habitat surrounding crops, but private buyers, keen on retaining consumer confidence in their products, may still require growers to take steps that go beyond government regulations.

"The real worry for me is that federal law will be interpreted as the floor rather than the ceiling of what farmers should do," said Karp. "There is this misguided idea that agricultural fields should be a sanitized, sterilized environment, like a hospital, but nature doesn't work that way."

Other co-authors of the study are Sasha Gennet, senior scientist at The Nature Conservancy; Christopher Kilonzo, Melissa Partyka and Edward Atwill, director of Veterinary Medicine Extension at UC Davis; and Nicolas Chaumont at Stanford University.

The UC Berkeley Center for Diversified Farming Systems, Berkeley Food Institute, The Nature Conservancy NatureNet Fellowship, and The Nature Conservancy of California helped support this research.

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  • Author - Sarah Yang, UC Berkeley, scyang@berkeley.edu, (510) 643-7741
Posted on Monday, August 10, 2015 at 11:26 AM

Helping winemakers sustainably produce premium wine

Ten large, shiny tanks stand near the Robert Mondavi Institute for Wine and Food Science at UC Davis, holding more than a year of rainwater and the key to processing food and drink during a drought. The water tanks, and the teaching-and-research winery they support, are showing students and winemakers throughout the world how to reduce processing costs, improve wine quality, and protect the planet's dwindling natural resources.

Professors Roger Boulton and David Block. (Photo: Kassie Borreson)
“It's about self-sufficiency,” says Roger Boulton, UC Davis professor of enology and chemical engineering. “We're demonstrating how you can operate a winery, brewery, or any food processing plant with the water that falls and the sun that shines on your roof.”

The work is the latest in more than a century of trail-blazing viticulture and enology science at UC Davis. UC Davis researchers are working with Cooperative Extension specialists and farm advisors with UC Agriculture and Natural Resources to help winemakers and grape growers sustainably produce premium wine.

Water is critical to winemakers in drought-stricken California and beyond. Grapes aren't a very thirsty crop to grow, but keeping fermentors clean is another story.

A typical winery uses four to six gallons of water after the grapes are harvested to produce one gallon of wine, and most of that water is used to wash equipment. Boulton and David Block, chair of the UC Davis Department of Viticulture and Enology, are developing self-cleaning fermentors capable of recycling 90 percent of that water. The goal: affordable technology and alternative practices that use less than one gallon of water to produce one gallon of wine.

Winemakers currently remove sticky, fermented, grape residue from tanks with water and elbow grease. Clean-in-place technology replaces hand-cleaning with an automated system that sprays tanks with diluted solutions of potassium hydroxide and potassium bisulfate.

“The dairy industry has used clean-in-place technology since the 1960s and the pharmaceutical industry since the 1990s,” says Block, a chemical engineer and enologist who helped the pharmaceutical industry manage clean-in-place technology before coming to UC Davis in 2008. “It's a little different with dairy and pharmaceuticals, where poor sanitation can kill you, but the concept is similar.”

Fermentors at UC Davis (Photo: Kassie Borreson)
So the water tanks near the Robert Mondavi Institute have two functions, to store water captured during the wet season to use during the dry season when it's needed most, and to filter and purify the water as it's used and reused to clean fermentors.

“We will filter and reuse that water at least five times, hopefully one day up to 10 times,” Boulton says. “It's not waste water. It has no phosphates, no nitrates, and no chlorine. Clean-in-place technology represents a huge potential for water and labor savings.”

Industry is starting to notice.

“Clean-in-place technology is very attractive to us,” says Ashley Heisey, director of winemaking at Long Meadow Ranch in Rutherford and a UC Davis viticulture and enology graduate. “Water is such a critical issue. Long Meadow Ranch owners Ted, Chris, and Laddie Hall built our facilities with great concern for the environment, and thanks to UC Davis, we can take it one step further.”

In Sacramento, grocer Darrell Corti from Corti Brothers Market says where UC Davis leads, winemakers will eventually follow.

“What we know about grape-growing and winemaking is primarily due to the work they do at UC Davis,” Corti says.

A longer version of this story is in the magazine Edible Sacramento.

Posted on Tuesday, August 4, 2015 at 8:26 AM

Have you tasted an avocado lately?

Eric Focht
The lab of Mary Lu Arpaia, a Cooperative Extension subtropical horticulturalist with UC Agriculture and Natural Resources (UC ANR) and the Department of Botany and Plant Sciences at UC Riverside, hosts an avocado tasting each month on the UCR campus. Attended typically by about 60 people, the tastings have grown in popularity over the years. 

Eric Focht, a staff research associate in the Arpaia lab, helps organize the tastings; the guacamole he prepares specially for the occasion serves as an additional attraction. Focht has been working on avocados since 1999, the year he joined UCR as a staff member. His relationship with the campus, however, began before then; his father, now retired, was a professor on campus.

Typically, participants of the avocado tastings sample six avocados which come from UC ANR's South Coast Research and Extension Center in Irvine. “Hass control fruit are purchased from or donated by a packing house,” Focht says.

First, participants do a visual assessment of the fruit, evaluating texture, size and color. Next they step into a room where they do the blind tastings.

“The data is compiled and used to assess, among other things, which of our new breeding selections shows promise and should be pushed for eventual release,” says Focht, whose duties include coordinating field activities, designing field layouts, generating maps and databases, selecting avocado varieties of interest, interacting with growers and the public, troubleshooting, and directing the day-to-day operations of the lab when Arpaia is away. 

Visual inspection of avocados
Focht's favorite avocado variety varies by year and season.

“Right now our 465518-99 has been performing very well,” he says, “but in former years, its peak season is February through April. In the fall, Reed is always a good fruit with good flavor and texture. I prefer a fruit that peels easily and has good flavor. If it doesn't peel clean from the skin, I tend to overlook it for something else with good flavor and convenient packaging.”

The avocado growing season varies from variety to variety. By planting out several varieties, it is possible to have avocados year round in one's garden. Focht explains that the growing season varies regionally as well.

“The season in San Luis Obispo is months later than it is in San Diego,” he says.

Most avocado acreage in California is currently in Northern San Diego County. Most avocado acreage in the U.S. is in California. Other states with avocado industries include Florida and Texas. Worldwide, avocados are grown in Mexico, Chile, Peru, Israel, Australia, South Africa and New Zealand.

Tasting avocados.
The California drought, now in its fourth year, is a concern for avocado lovers and scholars like Focht.

“An acre of avocado trees typically requires 2.5-4 acre-feet of water per year depending on weather and other factors,” he says. “The drought is resulting in lost acreage as farmers can either not afford or not find enough water for their trees. Successful farmers are having to modify their cultural practices to stay competitive.”

The next avocado tasting at UCR will be Aug. 12, 2015. For more information about the tastings, contact Focht.

Posted on Tuesday, July 28, 2015 at 9:26 AM

The health impacts of sugary drinks

Refined sugar (Photo: Ann Filmer)
Americans consume nearly three times the recommended amount of sugar every day, and about half the U.S. population consumes sugary drinks on any given day.

Excess sugar consumption contributes to obesity, tooth decay, early menses in girls, and chronic diseases including diabetes and heart disease. To add to the damage, doctors are now attributing too much dietary sugar to non-alcoholic fatty liver disease, which can lead to cirrhosis of the liver.

It's enough to make you sit up and listen to the warnings about too much soda, sugary drinks, and sugar-laden processed foods.

What is a sugary drink? It's any beverage, more or less, with added sugar or other sweeteners, including high-fructose corn syrup. The long list of beverages includes soda, lemonade, fruit punch, powdered fruit drinks, sports drinks, energy drinks, sweetened coffee and tea drinks, and many flavored milk products.

People are becoming aware of the concerns of too many sugary drinks, and steps are being taken to reduce their consumption. Some K-12 school districts across the nation are limiting sales of soda, and the City of Davis will soon require that restaurants offer milk or water as a first beverage choice with kids' meals.

UC Cooperative Extension, the county-based outreach arm of UC Agriculture and Natural Resources, is partnering with health agencies and conducting public service programs for youth and families about sugary drinks. UC ANR Cooperative Extension in San Joaquin County recently presented a "Rethink Your Drink" parent workshop in conjunction with the county's Office of Education, and Solano County Cooperative Extension is working with the California Department of public health to engage youth in "Rethink Your Drink" programs.

Sarah Risorto, UC IPM Program, refills her water bottle at a UC Davis water station. (Photo: Ann Filmer)

Lucia Kaiser, UC ANR Cooperative Extension nutrition specialist, co-authored a policy brief about California's rural immigrants who have poor-quality tap water, or perceive tap water to be bad. Kaiser, who is also a nutrition faculty member at UC Davis, noted that studies have found a link between water quality and consumption of sugary drinks, which is a concern in low-income communities that don't have resources for clean water.

As of this month (July 2015), UC San Francisco is no longer selling sugary beverages on its campus, and UCSF has launched a Healthy Beverage Initiative. UC Berkeley held a Sugar Challenge this year, and UC Davis is conducting a Sugar Beverage Study on women.

Scientists at UC San Francisco, UC Davis, UC ANR's Nutrition Policy Institute, and other universities are studying the health effects of sugar and implementing health outreach programs. And UC's Global Food Initiative is building on the momentum of excessive sugary-drink consumption.

A healthy alternative to sugary drinks? Water, of course. Many universities and public places are replacing traditional drinking fountains with water stations so that students and others can fill their own bottles and have water “on the go.” And UC President Janet Napolitano is working with the Nutrition Policy Institute on a bold and sensible request to place water on the USDA's MyPlate nutrition guidelines.

The next time you're thirsty, drink wisely to your good health.

Additional information:

Posted on Tuesday, July 28, 2015 at 8:23 AM

UC Global Food Initiative has fast start in first year

The UC Global Food Initiative has been a galvanizing force for bringing people together in new collaborative efforts. Credit: Elena Zhukova
In its first year, the University of California's Global Food Initiative launched food security efforts on every campus, held statewide conferences on sustainable fisheries and food justice, and appointed more than 50 student fellows to pursue projects.

That is just a taste of the work underway as faculty, students and staff from across the 10-campus UC system focus their collective power on food issues.

The Global Food Initiative has been a galvanizing force for bringing people together in new collaborative efforts, said UCLA's Wendy Slusser, who serves on one of the initiative's two dozen systemwide subcommittees.

“It's been a lightning bolt of energy that helps pull people together,” she said.

UC President Janet Napolitano first launched the Global Food Initiative on July 1, 2014. She spanned the state that day, meeting with Alice Waters at the Edible Schoolyard in Berkeley, the California State Board of Food and Agriculture in Sacramento, and UCLA students and campus leaders at their community garden in the Sunset Canyon Recreation Center.

The announcement was met with enthusiasm – and a bit of wonder at the audacity of the undertaking – as Napolitano and UC's 10 chancellors declared that UC would harness its people and power to put the university, state and world on a path to sustainably and nutritiously feed themselves.

A year later, the initiative is off to a fast start. All 10 UC campuses, UC's Division of Agriculture and Natural Resources, and Lawrence Berkeley National Laboratory have pitched in, building on existing efforts and creating new collaborations to develop, demonstrate and export solutions for food security, health and sustainability.

Strength in numbers

“The strength of the Global Food Initiative is its capacity to harness the resources and talents and energy around each of the UC campuses related to food in its broadest sense,” said Slusser, associate vice provost for the UCLA Healthy Campus Initiative. “The structure has allowed each campus to identify what it wanted to do, build on its strengths and learn from what the other campuses are doing.”

Napolitano has welcomed campus ideas, Slusser said. GFI is helping sponsor a UCLA food studies and food justice course/internship this summer for 20 undergraduate students. The course, which had a waiting list, will be offered again in the fall and next summer and could become a pilot for other UC campuses.

Slusser also praised the UC President's Global Food Initiative Student Fellowship Program. She will attend a July 20 symposium for GFI and Carbon Neutrality Initiative student fellows, noting that two UCLA fellows told her they now want careers in food. “They had never even considered it before,” Slusser said.

Sharing knowledge

Laura Schmidt, a UC San Francisco professor of health policy and lead investigator on the UCSF-led SugarScience initiative, serves on a GFI subcommittee that is organizing a workshop July 20 on leveraging research for food and agriculture policy change. The workshop will provide training on tools and ways that faculty members can interact with policy issues and policymakers.

“We have so much knowledge about health locked up in the ivory tower,” Schmidt said. “My role is to get information from scientific researchers into the hands of decision-makers and people who can move the dial on health. When the Global Food Initiative came along, it was, ‘Yes, I want to be a part of this.' The president is trying to get science out into the real world so it can have a positive impact on health.”

By providing policymakers with evidence-based information, UC researchers can help them address such problems as obesity and other chronic diseases, said Schmidt, who worked with supervisors on San Francisco's first-in-nation warning labels on sugary beverages. UC also can lead by example, she said, citing UCSF's new Healthy Beverage Initiative that phases out the sale of sugar-sweetened beverages at UCSF.

The Global Food Initiative's challenge is how to build on its momentum and create the infrastructure so that it sticks, she said.

“The food initiative spans agriculture, the environment and human health. That is really important. These issues intersect and overlap in powerful ways,” Schmidt said. “I think it was brilliant to bring this together.”

Here are some highlights of the Global Food Initiative's top accomplishments in its first year:

For more campus information, visit these sites: UC ANR, UC Berkeley, UC Davis, UC Irvine, UCLA, UC Merced, UC Riverside, UC San Diego, UCSF/SugarScience, UC Santa Barbara, UC Santa Cruz, Berkeley Lab.

Posted on Tuesday, July 21, 2015 at 7:30 AM
  • Author: Alec Rosenberg

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