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

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UCCE researcher seeks more colorful sweetpotatoes

Scott Stoddard holds Bellevue sweetpotatoes, a new variety identified in an evaluation trial that is a joint effort of UCCE, LSU and NCSU.
Americans draw their cuisine from a vast array of cultures, but on Thanksgiving most of us will sit down to eat essentially the same foods: roast turkey with cranberry sauce, stuffing, mashed potatoes with gravy, green bean casserole, dinner rolls and sweetpotatoes topped with melted mini marshmallows, followed by pumpkin pie for dessert.

Although you may call them candied yams, if they were grown in the U.S., the soft, orange roots you've smothered in butter and brown sugar are sweetpotatoes. If you don't add butter and sugar, sweetpotatoes are a healthful sweet treat, loaded with vitamins A, B-6, C and E and potassium and manganese.

In California, sweetpotato classes come in four colors:

  • Tan Jewell with orange flesh
  • Light yellow Jersey with white flesh
  • Purple Oriental with white flesh
  • Red Garnet with deep orange flesh

LSU professor Don LaBonte makes notes on sweetpotato varieties harvested in Merced County.
Scott Stoddard, UC Cooperative Extension advisor who evaluates sweetpotato varieties for production in California, is trying to identify lines with red and purple skin that grow and store well. It is a high priority for the industry because the Garnet class dominates many markets throughout the state. "Apparently, Californians like well-tanned sweetpotatoes, especially in Southern California," said Stoddard, who is based in Merced County.

“It's the same eye appeal as when people choose peaches,” Stoddard explained. “People tend to choose peaches with more red blush to the skin. Just as we tend to choose more colorful peaches, red-skinned sweetpotatoes are very popular, even more than the traditional tan skin sweetpotatoes that dominate in the rest of the United States.”

“The red variety is in high demand in LA, the Bay Area and Seattle markets,” said Jason Tucker, a grower and vice president of the CA Sweetpotato Council. “With our climate and sandy soil, we can grow any variety in California. It gives us so much flexibility and we're looking for new varieties. We can grow distinctive varieties, such as the Oriental variety, to meet demands even in other countries like Korea and Japan.”

Louisiana State University and North Carolina State University have the only two sweetpotato breeding programs in the U.S. For more than 50 years, UC has collaborated with the two universities in the National Sweetpotato Collaborators Trial, in which varieties are grown and evaluated in several states. Because the breeders are mainly interested in sweetpotatoes with light-colored skin, they used to discard the others. In 1998, Stoddard began screening their castoffs for high yields and sweet flavor in other colors.

Murasaki is a purple skin, white flesh sweetpotato cultivar introduced in 2008.
“Sweetpotatoes are expected to be on shelves 12 months a year so we need one that will store up to a year,” said Stoddard. Sweetpotatoes are harvested from July through October so he is looking for a red-skinned sweetpotato that offers better nematode resistance and holds up in storage longer. “The white ones and Orientals store well, but the reds break down in June and July.”

In addition to high yields and consistent flavor in a variety, Tucker said, “We are looking for varieties that maintain a high level of sugar, or sucrose levels, smooth skin and a consistent shape with a distinct color – purple, red or white.”

Before Stoddard introduces a new variety to a California field, he has the plant material virus-tested by Foundation Plant Services at UC Davis.

A purple sweetpotato with white flesh called Murasaki is a variety that emerged from Stoddard's test plots in 2008 and is now being grown commercially. Burgundy, released in 2014, is the first variety with red skin and orange flesh released in 30 years.  While Burgundy has better nematode resistance and improved storage characteristics, yields have failed to reach the numbers necessary to be commercially successful.

Burgundy is a red-skin, orange flesh variety released in California in 2014.
Sometimes when looking for a new red-skin cultivar, the UC Cooperative Extension advisor finds other desirable qualities. Stoddard is most excited about a tan-skin sweetpotato that he named Bellevue, after a road near the field where the variety was first evaluated and connects Atwater and Merced. “This variety has shown excellent yield potential combined with superior shape and skin quality in numerous test locations around the world, including North Carolina, Senegal, Israel and Australia,” he said. “It also has high nematode resistance and nice color.  But it's not red, though ironically it came out of the red-skin trial.”

“It takes a few years to see if they will be successful,” Stoddard said. “Things always show up once you move from a small plot to millions of plants, that's when their true personality comes out. We'll see how they do in different soil and in different areas. All varieties have their own personality.”

About 300 acres of Bellevue were grown in California in 2014. Although it may only be grown in California, Bellevue is patented by LSU. The varieties are patented by LSU and NC State to provide funding for their breeding programs.

“Scott is a highly valuable asset to Merced County growers, he provides all of our sweetpotato research,” said Tucker. “He brings new varieties from North Carolina and Louisiana to California to find a new variety that works well in our soil and climate. He analyzes them so we can make better decisions about which varieties we will grow.”

About 90 percent of the estimated 20,000 acres of sweetpotatoes grown in the state are in Merced County, around Atwater and Turlock, where the soils are sandy.

Posted on Tuesday, November 25, 2014 at 5:04 PM

Save water, but also save trees during drought

Drought-stressed trees are more prone to damage from diseases and insects.
Even as California enters the rainy season, the state is still in a drought. To avoid excessive landscape watering, we need to adjust the irrigation settings for our yards. At the same time we're trying to save water, we should also try to save our trees.

“Mature fruit trees and landscape trees are worth saving!” said Janet Hartin, UC Cooperative Extension advisor. “Recognizing early signs of drought stress is important because irreversible damage can occur that no amount of watering will correct.”

Two seasons without enough water can result in severe drought stress and even kill a tree, warned Hartin, who serves San Bernardino, Riverside and Los Angeles counties. Also, drought-stressed trees are more prone to damage from diseases and insects than non-stressed trees. 

Common symptoms of drought stress include

  • Wilting or drooping leaves that do not return to normal by evening
  • Curled or chlorotic (yellow) leaves that may fold or drop
  • Foliage that becomes grayish and loses its green luster
  • New leaves that are smaller than normal

“One or two deep irrigations with a garden hose several weeks apart in spring and summer will often keep these valued plants alive, especially if their roots are relatively deep,” she said.

Plants in full sun need more water.
For more precise water management, Hartin prefers micro-irrigation systems. “Drip irrigation is a wonderful tool for your ornamentals to apply the water directly to the root zone of the plant and reduce soil evaporation,” she said.

“An important thing to consider when you're trying to conserve water in the garden and landscape is that plant water requirements vary,” said Hartin, an expert in environmental horticulture. “Water needs are directly related to the evapotranspiration rate of each particular plant. To meet the water needs of plants, you have to replace the water used by the plant and the moisture that evaporates from the soil surface.”

Besides differences among water requirements among plant species, microclimates within a climate zone affect how much water a plant will need and how often a plant should be watered, as well.

“Landscape plants in urban heat islands surrounded by asphalt parking lots may require 50 percent more water than the same species in a park setting,” Hartin said.

Also, soil type plays a large role in how often landscape and garden plants should be irrigated. Sandy soils drain faster and take water in faster than those containing clay and require more frequent irrigation. Water can soak down 12 inches in 15 minutes in sandy soil, whereas the water may take 2 hours to reach the same depth in clay soil and will spread out more horizontally.

Plants that receive more shade require less water than the ones nearby in the sun.
Hartin, who works with UC Master Gardeners, suggests getting your hands dirty to determine when to water.

“Dig into the roots,” she said. “Take a handful of soil and squeeze it. That'll give you a good idea of whether the soil is really dry and crumbly, which means it's not holding any water, or if it's medium, where it's just starting to crumble, but still holding together fairly well. We recommend waiting to irrigate until the soil just starts to crumble.”

To see a video of Hartin's presentation “How to Save Water and Beautify Your Landscape the Sustainable Way,” visit https://www.youtube.com/watch?v=MN4b5DML-bs. For water-saving gardening tips in Spanish, visit http://bit.ly/1uZ6Ztq and http://bit.ly/1xHNwQo. You can also consult the UC Master Gardeners in your community for advice. Check http://camastergardeners.ucanr.edu to find the nearest UC Cooperative Extension office to speak with a Master Gardener.

The evapotranspiration rate of the same plant variety can vary in different parts of the state.
For more information about dealing with the drought, visit the UC California Institute for Water Resources website at http://ucanr.edu/drought.

Factors involved in irrigation scheduling

  • Plant water use 
  • Soil water holding capacity
  • Water infiltration rate
  • Plant rooting depth
  • Irrigation system output
Posted on Monday, November 24, 2014 at 12:04 AM
Tags: drought (13), garden (3), Janet Hartin (1), landscape (3), Master Gardeners (2)

UC students receive fellowships to study food issues

November 19, 2014

Pam Kan-Rice, (510) 206-3476, pam.kanrice@ucanr.edu

UC students receive fellowships to study food issues

Jacqueline Chang
Three University of California students will be working with scientists in the UC Division of Agriculture and Natural Resources (ANR) to study food security, nutrition education and agricultural research and extension as part of the UC President's Global Food Initiative Student Fellowships.

UC Berkeley senior Jacqueline Chang, UC Davis graduate student Samantha Smith and UC Berkeley doctoral candidate Kevi Mace-Hill each have been awarded a $2,500 fellowship.

The fellowships are supported by the UC Global Food Initiative, which UC President Janet Napolitano, together with UC's 10 chancellors, launched in July in an effort to help put UC's campuses, the state and the world on a pathway to sustainably and nutritiously feed itself. The UC Office of the President is providing $7,500 to each UC campus, ANR and Lawrence Berkeley National Laboratory for the fellowships, which will be awarded to both undergraduate and graduate students, with funds allotted at each campus's discretion in three $2,500 portions.

Samantha Smith
"Student involvement is critical to carrying forward UC's work to improve food security for UC students and others in California and beyond," said Barbara Allen-Diaz, UC vice president for Agriculture and Natural Resources. "These Global Food Initiative Student Fellowships will enable UC students Jacqueline Chang, Kevi Mace-Hill and Samantha Smith to work with UC scientists who study the food system and provide the latest research findings to farmers and consumers. Working together, we can continue improving access to nutritious foods."

Jacqueline Chang, UC Berkeley
Chang will work with Lorrene Ritchie, director of UC ANR's Nutrition Policy Institute, on a food security research project. The UC Berkeley senior, who is majoring in nutritional science with an interest in food insecurity, will assist in developing and conducting a survey to assess the prevalence of hunger and inadequate access to food among UC students across all 10 campuses. She will write a report and present the survey findings to Napolitano in the spring. Chang, a native of the Southern California community of San Marino, has worked with the Berkeley-based organization Feeding Forward to raise awareness of hunger, food insecurity and food waste.

Samantha Smith, UC Davis
Smith, a public health graduate student at UC Davis, with direction from Connie Schneider, director of UC ANR's statewide Youth, Families and Communities Program, will interview UC scientists about their research and extension efforts in agriculture, food and nutrition statewide and capture their stories to share with the public via blogs and social media. Smith, a native of Pleasanton, earned a bachelor's degree in psychology from Sonoma State University and is a California Wellness Foundation Fellow.

Kevi Mace-Hill
Kevi Mace-Hill, UC Berkeley
Mace-Hill will lead a group of graduate students that organizes seminars and workshops for students interested in careers in Cooperative Extension. Their goal is to improve graduate student preparedness for extension, outreach and applied research. Her fellowship will support the UC Berkeley graduate student-led Cooperative Extension Showcase.

The annual event brings UC Cooperative Extension advisors and specialists who conduct research and extension in nutrition, youth development, agriculture and natural resources to the Berkeley campus to discuss their work and network with graduate students. At the showcase in the spring, students will have an opportunity to meet potential mentors. Mace-Hill, a native of LaVeta, Colo., earned her bachelor's and master's degrees in biology at Wesleyan University in Connecticut and is currently pursuing her Ph.D. in biological pest control at UC Berkeley.

Through its Global Food Initiative, UC is building on existing efforts and creating new collaborations among its 10 campuses, affiliated national laboratories and ANR to improve food security, health and sustainability.

GFI fellows
GFI fellows

Posted on Wednesday, November 19, 2014 at 3:06 PM

Scholarships available for California Naturalist training in the Central Valley

California Naturalist training in an outdoor classroom.
Applications are now being accepted for scholarships to attend California Naturalist training in the San Joaquin Valley and central Sierra region in 2015.

To become a certified California Naturalist, trainees take part in 40 hours of classroom and field courses and complete a capstone project. More than 700 California Naturalists have been certified by UC Cooperative Extension since the program's inception in 2010. The 2015 training sessions will be offered with the Sierra Foothill Conservancy, the UC Merced Vernal Pools and Grasslands Preserve and the UC Merced Sierra Nevada Institute.

Partial scholarships will be awarded in two categories: Student Scholars Award and Service Award. The Student Scholars Awards are open to graduating high school seniors and currently enrolled college students. The Service Awards are open to people engaged in work (volunteer or paid) that directly impacts under-served communities.

The scholarships are intended to engage participants who will apply their experience by taking action in their own communities. To be eligible for a scholarship, aspiring naturalists are invited to fill out the online application at http://ucanr.edu/CalNatScholarship. Application review will begin in December 2014 and continue until all the scholarships have been awarded.

The California Naturalist program champions the state's unique ecology and engages volunteers in stewardship and study of California's natural world. A love of nature and a desire to share their passion prompt people to commit time to becoming and serving as California Naturalists. California Naturalist program uses a science curriculum, hands-on learning and volunteer service to inspire stewardship of the state's parks, wetlands, coastal areas, mountains, foothills and forests.

Four units of college credit are available for course participants through UC Davis Extension.

The following Central Valley California Naturalist programs are planned for 2015:

Sierra Foothill Conservancy. Classroom sessions: 6 to 8 p.m., Fridays March 13, 20, 27, April 10, 17, 24; Field sessions, Saturdays March 14, 21, 28, April 11, 17, 24.
Location: Fresno County
Cost: $350
Contact: Rosanna Ruiz, (559) 855-3473, Rosanna@sierrafoothill.org

UC Merced Vernal Pools and Grasslands Reserve. Spring 2015, class schedule TBD
Location: UC Merced
Cost: $350
Contact: Chris Swarth, (301) 769-8038, cswarth@ucmerced.edu

UC Merced Sierra Nevada Research Institute. Fall 2015, class schedule TBD (one week intensive)
Location: Yosemite National Park
Cost: $700
Contact: Becca Fenwick, bfenwick@ucmerced.edu , (209) 228-415

The scholarships were made possible by a grant from the Renewable Resources Extension Act, a program administered by the UC Division of Agriculture and Natural Resources.

Posted on Wednesday, November 19, 2014 at 7:20 AM

Coexist or perish, new wildfire analysis says

California fire hazard severity zone map. Click image to enlarge..
Many fire scientists have tried to get Smokey the Bear to hang up his “prevention” motto in favor of tools like thinning and prescribed burns, which can manage the severity of wildfires while allowing them to play their natural role in certain ecosystems.

But a new international research review led by the University of California, Berkeley, says the debate over fuel-reduction techniques is only a small part of a much larger fire problem that will make society increasingly vulnerable to catastrophic losses unless it changes its fundamental approach from fighting fire to coexisting with fire as a natural process.

The paper, “Learning to Coexist with Wildfire,” to be published in the Nov. 6 issue of the journal Nature, examines research findings from three continents and from both the natural and social sciences. The authors conclude that government-sponsored firefighting and land-use policies actually encourage development on inherently hazardous landscapes, amplifying human losses over time.

“We don't try to ‘fight' earthquakes – we anticipate them in the way we plan communities, build buildings and prepare for emergencies. We don't think that way about fire, but our review indicates that we should,” said lead author Max Moritz, Cooperative Extension specialist in fire at UC Berkeley's College of Natural Resources. “Human losses will only be mitigated when land-use planning takes fire hazards into account in the same manner as other natural hazards, like floods, hurricanes and earthquakes.”

The analysis looked at different kinds of natural fires, what drives them in various ecosystems, the ways public response to fire can differ, and the critical interface zones between built communities and natural landscapes. The authors found infinite variations on how these factors can come together.

“It quickly became clear that generic one-size-fits-all solutions to wildfire problems do not exist,” Moritz said. “Fuel reduction may be a useful strategy for specific places, like California's dry conifer forests, but when we zoomed out and looked at fire-prone regions throughout the Western United States, Australia and the Mediterranean Basin, we realized that over vast parts of the world, a much more nuanced strategy of planning for coexistence with fire is needed.”

Planning for co-existence

If humans choose to live in fire-prone regions, fire must be managed on par with other naturally occurring hazards, the authors argue, and research must seek to understand what factors and outcomes we can and cannot affect.

One common tool is applicable to the vast array of ecological and social science interactions at the critical wildfire/urban interface: more effective land-use planning, along with the regulations that guide it.

This demonstration structure was designed to resist fire.
The authors recommend prioritizing location-specific approaches to improve development and safety in fire-prone areas, including:

  • Adopting new land-use regulations and zoning guidelines that restrict development in the most fire-prone areas;
  • Updating building codes, such as requiring fire-resistant construction to match local hazard levels and encouraging retrofits to existing ignition-prone homes;
  • Implementing locally appropriate vegetation management strategies around structures and neighborhoods;
  • Evaluating evacuation planning and warning systems, including understanding situations in which mandatory evacuations are or are not effective;
  • Developing household and community plans for how to survive stay-and-defend situations; and
  • Developing better maps of fire hazards, ecosystem services and climate change effects to assess trade-offs between development and hazard.

As an example of positive steps, the report cites new fire danger mapping efforts, including an existing fire hazard severity zone map that guides building codes in California. Produced by the state's Department of Forestry and Fire Protection, the current map does not explicitly incorporate locally varying wind patterns, which influence the worst fire-related losses of homes and lives, but future iterations will include these data.

Fire ecology and climate

The authors underscore that wildfires are a natural part of many ecosystems and can have a positive long-term influence on the landscape, despite people labeling them as “disasters.” They can stimulate vegetation regeneration, promote a diversity of vegetation types, provide habitat for many species and sustain other ecosystem services, such as nutrient cycling.

Around the world, the numbers, sizes, and intensities of fires vary greatly. In some ecosystems, big, severe wildfires are natural events and more climate-driven – by drought or high winds – so fuel reduction is not a very effective tool in these locations. By contrast, many ecosystems that would naturally experience frequent lower-severity fires may respond to vegetation management aimed at both reducing fire hazard to humans and restoring crucial ecosystem processes. But, the authors agree, where fuel reduction is an appropriate goal, it would ideally be achieved by letting wildfires do their job.

A changing climate will complicate management strategies.

“How should future fire patterns compare to this historical variability? That's the big question,” Moritz said.

Describing wildfire as “one of the most basic and ongoing natural processes on Earth,” the authors call for a paradigm shift in the way society interacts with it, changing to an approach that achieves long-term, sustainable coexistence that benefits the planet's ecosystems on the landscape scale, while minimizing catastrophic losses on the human scale.

“A different view of wildfire is urgently needed,” said Moritz. “We must accept wildfire as a crucial and inevitable natural process on many landscapes. There is no alternative. The path we are on will lead to a deepening of our fire-related problems worldwide, which will only become worse as the climate changes.”


Posted on Wednesday, November 5, 2014 at 11:05 AM
Tags: fire (5), Max Moritz (3), wildfire (9)

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