- Author: Jeannette E. Warnert
Aflatoxin can form on a wide variety of crops, from corn to cotton to tree nuts. Careful management practices help keep levels low, but still hundreds of thousands of pounds of pistachios are rejected each year due to the presence of aflatoxin.
UC Davis plant pathologist Themis Michailides and his team of researchers at Kearney discovered how to expose pistachio trees to the spores of a beneficial fungus that displaces the fungi that produce aflatoxin. Displacing aflatoxigenic fungi with a beneficial fungus has never before been done in tree crops.
“We’ve gotten great results,” Michailides said. “The reduction in aflatoxin contaminated nuts has been up to 45 percent. We anticipate higher reduction with application of the beneficial fungus for multiple years and on larger acreage.”
The new process was approved by the U.S. Environmental Protection Agency in February and the California Department of Pesticide Regulation in May, in time for 60,000 acres of the 2012 California pistachio crop to receive the innovative treatment.
“This is a big step,” Michailides said. “There will be a tremendous savings to pistachio growers by reducing rejections and the need for resorting nuts before going to market.”
Aflatoxin was discovered in the 1960s when a flock of turkeys in England died after eating contaminated feed. Aflatoxin is produced by certain strains of the fungus Aspergillus flavus, which is commonly found in soil and decaying vegetation. Aflatoxin is a resilient foe. Roasting nuts does not destroy the toxin. Other crops, such as corn and cottonseed used as animal feed, can be treated with ammonia to reduce aflatoxin, however ammonia treatment is not possible for human food, such as tree nut crops.
All shipments of pistachios are tested for aflatoxins, and are rejected in Europe if contamination exceeds 10 parts per billion and in the United States if shipments have more than 15 parts per billion.
The use of beneficial fungi to fight aflatoxin was first discovered and investigated by Peter Cotty, a USDA Agricultural Research Service plant pathologist located in the School of Plant Sciences at the University of Arizona. Cotty’s research focuses on reducing aflatoxin presence in corn and cottonseed. In collaboration with Cotty, Michailides and his colleague Mark Doster, staff research associate in the Michailides lab at Kearney, found that Aspergillus flavus 36 (AF36) can be introduced into an orchard by inoculating “dead” wheat seeds and then dispersing the seeds on the orchard floor. Dew and soil moisture spur the development of harmless spores that colonize pistachios and prevent colonization by toxigenic fungus strains.
The Kearney scientists are continuing their cooperation with USDA’s Cotty as they expand the research to almonds and figs.
“We’re conducting micro-plot experiments with the almond industry at Kearney,” Michailides. “We hope to get an experimental use permit soon to make the treatment available to almond growers.”
Michailides’ aflatoxin research was funded by USDA, the California Pistachio Research Board, the Almond Board of California and a UC Discovery Grant. The research was made possible by the involvement of cooperating pistachio growers who opened their orchards to scientists for conducting AF36 trials.
- Author: Pamela Kan-Rice
While earning a bachelor’s degree in home economics education from South Dakota State University, Johns took a summer job with South Dakota Cooperative Extension teaching at an Indian reservation.
“One of my assignments was to teach nutrition to families on the reservation,” Johns recalls. “That’s where I learned that delivering a scripted program is not always the most effective. The beauty of Cooperative Extension is having the flexibility to tailor educational programs to meet the needs of your clientele.”
Although the Brookings, S.D., native had participated in 4-H and her father was a Cooperative Extension economics specialist at South Dakota State University, Johns didn’t really know the community-based educational organization until she began working for UC Cooperative Extension in 1974 as an advisor for Plumas, Sierra, Lassen and Modoc counties. She coordinated the 4-H youth development and nutrition education programs for those four counties until 1983, when she became a UCCE advisor in El Dorado and Amador counties in the same role.
In 1985, Johns transferred to San Mateo and San Francisco counties to serve an urban population as the UCCE 4-H youth development and nutrition, family and consumer sciences advisor. One of her projects was starting a school garden in Pacifica. She recruited senior citizens to teach the children how to grow vegetables. The senior citizens’ requests for guidance led her to develop TWIGS, 30 gardening and nutrition lessons for “Teams With Intergenerational Support.” Published in 1997, Johns continues to receive requests for the TWIGS curriculum. More than 3,500 copies have been sold to schools, after school programs, parks and recreation and YMCA programs, senior centers, nutrition networks and food banks in 22 states. California’s Department of Education uses TWIGS as an example of gardening curricula addressing education standards.
While serving the Bay Area, Johns earned a master’s degree in public administration with an emphasis in human resources at Notre Dame de Namur University in Belmont. In 2005, Johns was promoted to director for UCCE in San Francisco and San Mateo counties and director of Elkus Ranch, an environmental education and conference center in Half Moon Bay that provides hands-on learning experiences for San Francisco Bay Area youth. In 2011, Johns was also named director of UCCE in Santa Clara County.
In addition to promoting nutrition education and agricultural literacy through gardening, Johns has studied teen pregnancy. An article that she coauthored, “Best Practices in Teen Pregnancy Prevention,” was one of the most visited online articles of the Journal of Extension in 2005.
A founding member of the San Mateo Food Alliance System and a member of the statewide School Garden Network, Johns and nonprofit partners Hidden Villa and Collective Roots recently received a three-year grant of $173,000 per year from Sequoia Healthcare District to improve children’s health through garden-based learning.
While there have been groups who advocate for school gardens and those who promote nutrition, they haven’t always worked together in the past, says Jennifer Gabet, nutrition manager for Sequoia Healthcare District. Through a unique collaboration and development of a model teaching garden, 1, 2, 3 Let’s Grow! will emphasize growing edible plants, providing the students with fresh produce to eat and demonstrating how to prepare the fruit and vegetables they grow.
“Marilyn has been able to bring the two groups together, to see the garden as a mechanism to improve the school food environment and nutrition education,” Gabet said. “They teach science, but it doesn’t always include nutrition – discussion of the benefits of the foods grown and how students and families can include them in their diets to support their health.”
“This grant is pretty exciting,” Johns said, explaining that it incorporates nutrition education into hands-on activities for children, which is a more effective teaching method. She oversees the UC Master Gardener volunteers and UCCE nutrition educators who will be training K-12 teachers, parents and other participants at up to 34 schools on how to enhance children’s learning while gardening.
In retirement, Johns, who has been granted emeritus status, looks forward to continuing to contribute to garden-based learning as well as spending time with family and traveling for pleasure.
- Contact: Kathy Keatley Garvey
A team of nine entomology, cancer and nutrition researchers, in work published in the June 25 edition of Proceedings of the National Academy of Sciences, found that this new class of drug molecules stabilized the natural molecules and "effectively blocked neuropathic pain" - or pain caused by nerve damage. The research, conducted on rodents, is expected to lead to an orally active drug candidate for human clinical trials.
"This discovery offers a promising new approach to controlling chronic pain in diabetics," said lead author and project scientist Bora Inceoglu of the Bruce Hammock lab based in the Department of Entomology. "We were initially looking at anti-inflammatory compounds which regulate a key branch of an inflammatory pathway. These compounds are highly selective and inhibit a key enzyme called soluble epoxide hydrolase. Inhibition of this enzyme successfully blocks pain sensations."
"Our data indicate that this drug candidate is more effective on neuropathic pain caused by diabetes than any of the prescription drugs now on the market," said Hammock, a distinguished professor of entomology who holds a joint appointment with the UC Davis Comprehensive Cancer Center.
The research is significant in that in the United States alone, diabetics total 25.8 million or 8.3 percent of the population, and millions more - estimated at 79 million - are pre-diabetic, according to the American Diabetes Association. The Centers for Disease Control and Prevention tallies the economic burden of diabetes at approximately $170 billion a year.
Professor Daniele Piomelli, director of drug discovery and development at UC Irvine and who holds the Louise Turner Arnold Chair in Neurosciences, said that the study holds promise. He was not involved with the UC Davis research.
"Current medicines do not control well chronic pain produced by damage to the nerves," said Piomelli, professor of anatomy, neurobiology, and biological chemistry. "The study by Hammock and collaborators identifies a new class of chemical compounds that could change this situation. These compounds act by boosting natural signals, produced by the body, which curb both inflammation and pain. Exploiting the body's own 'medicines' is a great approach to creating safer medicines."
Piomelli cautioned that the experiments "were conducted in animals and need therefore to be confirmed by clinical trials."
UC Davis School of Veterinary Medicine anesthesiologist and pain specialist Alonso Guedes, also not involved in the study, said that the research shows that "stabilization of a class of bioactive lipid greatly reduces pain derived from nerve lesions. This novel and emerging knowledge may help fulfill a critical medical need for millions of animals and people afflicted by such pain modalities."
For the study, the UC Davis researchers used the Type I diabetes-induced pain model.
"Although Type II diabetes, associated with obesity, hypertension and metabolic disorders, is more prevalent in humans, to study the analgesic effects we selected Type I diabetes since pain manifests in an accelerated manner," said co-researcher and pharmacology doctoral candidate Karen Wagner. "In Type II diabetes patients, the occurrence of pain is delayed by many years of pre-diabetic or diabetic state, whereas our model affords a very rapid onset of pain."
Team member Fawaz Haj of the Departments of Nutrition and Internal Medicine, a leading nutrition and diabetes expert and a collaborator with the Hammock lab on diabetes, said that, "Intriguingly, in this study, acute treatments with soluble epoxide hydrolase inhibitors did not significantly affect the diabetic status of the animals, such as blood glucose levels and responses to insulin, indicating a selective effect on pain sensation. Neuropathic pain is a major co-morbidity of diabetes and an important debilitating factor that reduces the quality of life and this study accomplished a first in showing analgesic effects of soluble epoxide hydrolase inhibitors."
The researchers worked on a physiological pathway that was largely unknown until recently. When the enzyme, soluble epoxide hydrolase, is inhibited, "what happens is that the biological effects of a group of lipid metabolites, that are degraded by this enzyme, accumulate to effective levels," Hammock said.
"It turns out that a major function of these lipid metabolites is to selectively block pain sensation while sparing other types of sensations," Hammock said.
Inceoglu described neuropathic pain as "a debilitating condition and very difficult to treat with available painkillers or analgesics. Most analgesics are ineffective while those that reduce neuropathic pain often come with a variety of side effects that negatively affect the quality of life."
Nerve damage may be the result of trauma and chemotherapy agents or even diabetes itself. In diabetes, high levels of blood glucose damage the fine endings of sensory neurons that normally transmit pain-related information, the scientists explained. The aberrant signaling from the damaged neurons is interpreted as extreme sensitivity to touch and sometimes insensitivity to heat. "Even an innocuous touch, such as buttoning a shirt or the collar rubbing against the neck, or the vibration of being in a bumpy car ride can result in extreme pain," Inceoglu said.
"Almost half of advanced diabetic patients suffer from this painful condition which worsens as diabetes progresses," Inceoglu said.
Nerve and vascular damage can lead to gangrene and amputation. In advanced stages, the nerve damage leads to life-threatening heart and kidney diseases.
Physicians face a dilemma in selecting the right painkillers for the right conditions and with the least possible side effects, the UC Davis researchers said. Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs), for example, are completely ineffective for neuropathic conditions, Hammock said. Narcotics, like opium, can be addictive; withdrawal is difficult.
"Therefore, there is a great need to discover new approaches in combating pain," Hammock said. "New medications will effectively increase the number of choices for patients and physicians in treating intractable pain. Our study shows that the novel approach is effective and may not lead to the known side effects of narcotics or anti-depressants."
"It is still too early for these new compounds to reach the stores as analgesic drugs, since FDA approval takes a decade with very thorough evaluations," Inceoglu said. "However, once the feasibility of this approach is demonstrated, hopefully a major hurdle in moving toward clinical application is overcome."
The research, funded by the National Institutes of Health, supports earlier studies at UC Davis and later at Medical College of Wisconsin that showed the natural epoxy-fatty acids are analgesic molecules.
"Although very effective in blocking pain, unlike narcotics, these molecules do not affect coordination skills of animals," Inceoglu said.
The research team included Bora Inceoglu, Karen Wagner, Jun Yang, Nils Schebb, Sung Hee Hwang and Christophe Morisseau, all of the Department of Entomology; Bruce Hammock, Department of Entomology and UC Davis Comprehensive Cancer Center; Ahmed Bettaieb of the Department of Nutrition; and Fawaz Haj of the Departments of Nutrition and Internal Medicine.
"This is an interdisciplinary effort among neurobiologists, diabetes specialists, organic chemics and analytical chemists," said Hammock. "We could not have done this without sophisticated mass spectrometry equipment."
"The emerging mass spectrometric technique allowed us to analyze the tiny amounts of natural bioactive compounds, contributing to this pain discovery," said Yang.
Hammock directs the campuswide Superfund Research Program, the National Institutes of Health Biotechnology Training Program and the NIEHS Combined Analytical Laboratory. He is a Fellow of the Entomological Society of America, a member of the prestigious National Academy of Sciences, and the recipient of the UC Davis Faculty Research Lecture Award in 2001 and the Distinguished Teaching Award for Graduate and Professional Teaching in 2008.
Hammock's initial research involved regulating the development of insect larvae.
- Contact: Mary Louise Flint
“The disease has killed thousands of black walnut trees in California’s landscape and is threatening commercial walnut trees as well,” said Mary Louise Flint, UC Cooperative Extension specialist in the Department of Entomology at UC Davis and UC Statewide IPM Program.
Thousand cankers disease has now moved into the eastern U.S., where it threatens valuable stands of black walnut timber east of the Mississippi. Once in trees, the beetle and fungus cause gradual decline and eventual death by killing the vital phloem tissue beneath the bark.
The guidelines and trapping methods were developed by a team of entomologists from UC Davis and the USDA Forest Service Pacific Southwest Research Station in Davis. In 2010 and 2011, the scientific team discovered and patented an aggregation pheromone for the beetle and conducted scientific trials in northern California.
Late in the summer of 2011, they demonstrated the efficacy of the pheromone as a flight trap bait for detecting new populations of the beetle in Tennessee, Virginia and Utah. The demonstration-research project was extended to Pennsylvania in 2012. The bait lures both male and female beetles into a small plastic funnel trap. The team worked with a commercial partner, Contech Enterprises, Inc., to develop the technology.
As the eastern black walnut resource is valued at over $500 billion, the stakes are high for containing thousand cankers disease if it is introduced into key timber-producing states like Indiana and Missouri.
The study team is also using the traps and pheromone in research in California to learn more about biology and potential management strategies for the beetle in commercial walnut orchards and wildland areas.
The trapping guidelines are presented in a full-length document with color photographs and details on identifying the beetle, a short version for use in the field, and two video clips that demonstrate how to set up and service the traps. Find them at http://www.ipm.ucdavis.edu/thousandcankers.
In addition to Flint, members of the UC Davis and USDA scientific team and authors of guidelines are Steven J. Seybold, insect chemical ecologist, USDA Forest Service, based at Pacific Southwest Research Station in Davis; Paul L. Dallara, postdoctoral research scientist in the Department of Entomology at UC Davis; and Stacy M. Hishinuma, graduate student, Department of Entomology at UC Davis.
- Author: Jeannette E. Warnert
“I started and just kept going,” said Charlie Summers, a research entomologist who was first affiliated with UC Berkeley and later affiliated with UC Davis. Summers ends a 42-year stretch at Kearney when he retires June 30.
Summers grew up on a family farm in Utah and always knew he wanted a career in agriculture. He said he decided at age 12 to go to college, “when I was at the wrong end of a short-handled hoe.”
Summers earned bachelor’s and master’s degrees in zoology and entomology respectively at Utah State University in Logan, Utah, and a doctorate degree in entomology at Cornell in 1970, the same year he started at Kearney.
“The job at Kearney was an absolutely perfect fit for me,” Summers said. “It was a dream job. I look forward to coming to work every morning and would sometimes shake my fist at the sun going down at night. I’ve loved every minute I’ve been here.”
Summers studied a wide range of pest problems in field and vegetable crops. He developed economic thresholds for more than a dozen pests and management strategies for equally as many crops. Among the most challenging pests was the alfalfa weevil, he said. It has been particularly unresponsive to biological control and host plant resistance.
“It is one of the insects that has defied everything we’ve thrown at it except pesticides,” Summers said.
Silverleaf whitefly also posed a tremendous challenge during his career. Silverleaf whitefly was first found in the United States in Florida poinsettia crops during the mid-1980s. Eventually it made its way to a wide range of crops in California, resulting in severe economic losses to growers. Heavy applications of traditional chemicals needed to control the pest caused growers’ costs to increase. The production of some crops ceased altogether because of the extent of silverleaf whitefly damage.
In time, Summers and his colleagues developed a protocol for monitoring and managing the silverleaf whitefly. Light populations are controlled by native and introduced parasites and predators. More severe infestations must still be treated with pesticides.
Another major challenge was the corn leafhopper. The pest first made its way to California in the early 1940s, but didn’t become a serious problem until the end of the 1990s, when it was found to transmit corn stunt disease.
“Corn stunt disease caused plants to form few or no ears of corn. Some farmers’ yields were cut in half,” Summers said. “We worked out a strategy for scheduling planting to avoid the most serious damage. That’s worked out well for growers.”
Crops grown on silver mulch produced significantly higher yields of marketable fruit than did those grown on bare soil, the researchers concluded. Reflective mulch has been used by organic and conventional farmers up and down the valley and in Southern California to grow vegetables. Home gardeners have also applied these research results to garden beds by using aluminum foil as mulch.
Although Summers did not technically have a Cooperative Extension component to his position – he was among the last scientists hired to devote 100 percent of their time to research – Summers made it a point to work closely with farm advisors and specialists to convey research results to farmers.
“Extension work has been one of the most enjoyable things I’ve done,” he said. “I’ve worked with farm advisors on research projects, farm calls and given hundreds and hundreds of extension talks at their grower meetings.”
Summers has also authored more than 200 articles, book chapters and research papers, most of them peer reviewed.
Over the years, Summers said, the objective of his job – to help farmers develop successful pest management strategies – stayed the same, but technological advances dramatically changed the way he did his work.
“We’ve had the advent of computer technology, the use of mathematical models, work that can now be done at the DNA level. It’s put a whole new face on our ability to do research,” he said.
Nevertheless, he said, nothing can replace what he considers the essence of the Agricultural Experiment Station model: to personally assist growers.
“To me that’s the most important job we performed,” Summers said. “I hope this work continues.”
In retirement, Summers plans to move back to Utah to live near his sister and nephews and spend time pursuing his favorite pastime, fly fishing.
“I’ll be living 15 minutes from the Wasatch Mountains,” Summers said. “There’s a lot of good fishing there.”