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

Posts Tagged: almonds

Duncan’s research ‘blew up preconceived ideas,’ improved almond, peach, grape production

 

Roger Duncan, shown talking with Ken Shackel, UC Davis pomologist, and Helen Dahlke, UC Davis hydrologist, in an almond orchard for a groundwater recharge project, collaborated with numerous UC ANR colleagues on research.

Roger Duncan, UCCE farm advisor in Stanislaus County, retires after 36 years

For more than three decades, tree fruit and nut growers have depended on the advice of Roger Duncan, UC Cooperative Extension pomology farm advisor in Stanislaus County, to improve their production practices. Duncan, whose research and extension program focused on almonds, peaches, grapes and other tree crops, retired July 1.

“Roger Duncan has been an extraordinarily relevant researcher for the predominant crops in Stanislaus County,” said Rep. John Duarte, owner of Duarte Nursery in Hughson. “His research has encompassed rootstock and variety selection, tree spacing, chemical inputs and spraying, fertilizers, pruning and replanting amongst other projects.”

Duncan began working for UC ANR in 1988 as a field assistant to Integrated Pest Management advisor Jim Stapleton after earning a master's degree in plant science and plant pathology from Fresno State and a bachelor's degree in the same subjects from UC Davis. In 1990, he became a UC Cooperative Extension in pomology farm advisor in Stanislaus County.

“I am most proud of the trust I have developed with the growers and other clientele,” said Roger Duncan, who retired as UC Cooperative Extension pomology farm advisor in Stanislaus County.

During Duncan's tenure, the planted acreage of tree and vine crops has tripled in Stanislaus County to nearly 1,900 farms on over 230,000 acres. His research has helped to improve production efficiency through improved rootstocks, crop varieties and production practices.

“Roger provides growers with resources and tools on nutrition, sprays, nutrient deficiencies, calendars, costs, pest management and other horticultural practices,” Duarte said. “His work has had significant impact on the productivity and quality of almonds, peaches and grapes. Breeders, universities, nurseries, growers and marketers have all gained from the wisdom and dedication of Roger Duncan.”

Growing up in Modesto, Duncan wasn't raised on a farm. “I had friends whose families farmed orchard crops, so I had some exposure,” he said. “I caught the Extension bug while working as a summer intern for the pomology advisors in the Stanislaus County UCCE office after I graduated with my B.S. That is what inspired me to return to school with the goal of being a pomology farm advisor.”

Duncan hosted several field events each year. For over 20 years, he coordinated the annual North San Joaquin Valley Almond Days, which attracted more than 500 attendees.

Reducing production costs

To help growers lower production costs, Duncan introduced orchard practices aimed at reducing hand labor and other inputs. As a result of his research, minimal pruning has become the norm in California almond production, reducing input costs and carbon output and increasing yield. He also improved monitoring and management techniques of established and invasive diseases and insect pests.

“The practical applications Roger brings to the grower community are invaluable,” said Mel Machado, Blue Diamond Almonds vice president for member relations and Stanislaus County almond grower. “His minimal pruning study stood growers on their heads. People had preconceived ideas about pruning. He blew that up. His research showed that after you get the tree's frame, all you need to remove are the dead and occluded branches. With the market depressed, we needed to cut costs. He said, ‘You don't need pruning.' Now I'm growing bushes.”

Art Bowman, a crop adviser with Salida Ag Chem, agreed that Duncan's pruning research had an impact. “Roger's pruning trial that lasted over 20 years was a much-discussed subject among growers,” Bowman said. “Growers' pruning practices definitely changed due to Roger's research, with early emphasis on structural development and, later in the tree's life, concentrating on tree accessibility and deadwood removal.”

In 1990, when Duncan joined UC Cooperative Extension, California had 408,700 acres of almonds, according to the California Agricultural Statistics Service. Now the state has over 1.5 million acres of almonds.

About 75% of the farms Duncan has served have 40 acres or less, farmed by “small” or “part-time” farmers, who needed to learn basic horticulture and pest management. Stanislaus County also is home to some very large, sophisticated growers, who Duncan has kept apprised of new technology.

“I believe that personal interaction offers the most memorable means of information transfer, which is why I held an average of 12-plus extension events per year, gave 18-plus extension presentations per year, and went on an average of over 75 individual farm calls per year,” Duncan said. He also provided information via videos, blogs, podcasts, radio shows, newsletters, news media and extension publications as well as commodity boards.

Along with Duncan's research, Bowman has appreciated his availability. “Roger was always ready to take a call, make orchard visits and listen to a grower's concern or problem,” he said. 

In 1997, Duncan began hosting twice monthly Tree & Vine Integrated Pest Management breakfast meetings for pest control advisers and growers to discuss current and potential pest threats. These meetings have continued for 28 years.

Duncan and the Tree & Vine Integrated Pest Management breakfast meeting team won the California Department of Pesticide Regulation’s IPM Innovator Award in 2016.

He speaks ‘farmer'

Machado attributes much of Duncan's success to his communication skills. “His research is scientific and he speaks ‘farmer,'” he said.

Machado gave rootstock as an example. “Roger is my rootstock resource; he knows rootstocks better than anybody,” he said. “His rootstock trial is dirt simple. There's a different rootstock every five trees. You can see walking down the row the differences in the rootstocks.”

From his field evaluations, Duncan identified a complex hybrid rootstock that is highly tolerant to ring nematode, bacterial canker and salt toxicity. He found other hybrid rootstocks that boost crop yield while reducing risk from soil chemistry and soil-borne disease challenges, enabling almonds to be grown in the marginal soils on the west side of the North San Joaquin Valley. To help growers choose the appropriate rootstock for their soil, he wrote a comprehensive ANR publication, made a video and worked with the UC Fruit & Nut Center to create an interactive rootstock comparison website.

Over the last 15 years, use of hybrid almond rootstocks has increased dramatically. Burchell Nursery now sells approximately 40% of their trees on hybrid rootstock compared to less than 5% of almond trees 15 years ago, and more than 95% of Duarte Nursery almond trees are on hybrid rootstocks, according to Duncan. 

“We've worked with Roger for years, back when he didn't have a mustache and then when he had a mustache,” said Robert Longstreth, who grows almonds, walnuts and cherries.

“Roger does research in the area you need, not frivolous stuff that you don't need,” said Longstreth, who has benefited from Duncan's research on pruning, rootstocks, irrigation timing, plant nutrition and disease control. “He's thought very highly of by almond growers. When he has something to say, people listen.”

The UCCE farm advisor has overseen long-term trials to learn how to design and maintain an almond orchard to capture early production, maintain long-term yields and maximize profits. “In the first 17 years of the orchard design project, I increased cumulative net profits by up to $14,000 per acre, including increased yield while reducing labor and carbon inputs,” Duncan said.

Influenced by Duncan's tree-spacing research results, growers have increased almond tree density by 20% per acre statewide, leading to higher crop yields, longer-living orchards and better farm economic sustainability.

As California's expert on almond rootstocks and almond orchard design, Duncan has taught the subjects for the UC Almond Production Short Course, was lead author on the UCANR publication “Almond Rootstocks,” wrote the rootstock chapter, and co-authored the orchard design chapter of the UC Almond Production Manual. He was invited to Chile, Spain and Australia to share his expertise with growers there.

“I felt very lucky to serve as an advisor in the same county where I was born and raised,” Duncan said.

Expanded programs for kids and gardeners

In addition to being a farm advisor, Duncan served as director of UC Cooperative Extension in Stanislaus County from 2011 through 2013 and again from 2017 through 2020. As the UCCE county director, he acquired new county funding to hire a 4-H youth development program representative in 2018 to provide more learning opportunities for local, underrepresented children.

That year, he also acquired county funding to hire a full-time Master Gardener coordinator and launched the first UC Master Gardener Program in the county.

“I felt very lucky to serve as an advisor in the same county where I was born and raised,” Duncan said. “I am most proud of the trust I have developed with the growers and other clientele.”

Professional awards

Recently, Duncan's peers at UC ANR honored him with a Distinguished Service Award for his outstanding extension program, which gave growers the data and confidence to adopt orchard practices that have bumped up the productivity and economic value of California almond orchards.

The popular breakfast meetings to discuss pest management earned Duncan and his UC Cooperative Extension farm advisor colleagues the Entomological Society Award of Extension Excellence and the California Department of Pesticide Regulation's IPM Innovator Award. The California Legislature also recognized the breakfast club's commitment to sustainable pest management.

Recognizing Duncan's extraordinary contributions, the university recently granted him emeritus status.

“I have a lot of respect for the other farm advisors, but Roger is at the top of the pile,” said Machado, who has served on Almond Board committees with Duncan and known him since he joined UC Cooperative Extension. “I'm going to miss him. You can absolutely count on him.”

Congressman and nurseryman Duarte added: “While he will be sorely missed by us in his role of pomology advisor for the University of California, we hope that he keeps his interest, and continues to influence the food production industry in the Central Valley.”

Posted on Monday, August 5, 2024 at 3:49 PM
Tags: almonds (55), Roger Duncan (17)

Climate change to drive surge in insects that attack almonds, peaches, walnuts

Oriental fruit moth is a major pest that damages peaches. Photo by Jack Kelly Clark

UC study predicts three major pests to emerge earlier, produce more generations

As a result of climate change, the Golden State's farms are expected to face a surge in agricultural pests, which poses a threat to California's specialty crops industry. Populations of three major insect pests – codling moth, peach twig borer and oriental fruit moth — are projected to increase mainly due to rising temperatures, according to a study recently published in the journal “Science of the Total Environment” by a team of researchers at University of California Agriculture and Natural Resources and the U.S. Department of Agriculture California Climate Hub.

“These three pests are notorious for infesting most of the walnut, almond and peach orchards of California, causing extensive damages by reducing quality of fruits and nuts,” said study co-author Jhalendra Rijal, UC Cooperative Extension integrated pest management advisor and entomologist for Stanislaus, San Joaquin and Merced counties.

Climate change can lead to shifts in the timing of seasons, including warmer winters, earlier springs and hotter summers, and these conditions can disrupt the natural life cycles of pests.

 The California research is supported in part by USDA's National Institute of Food and Agriculture. NIFA National Program Leader Amy Ganguli said the California project is a strong example of the  work being done through AFRI's Extension, Education & USDA Climate Hubs Partnership.

 “A key element of this grant program to link critical research findings like this with timely education and outreach efforts to producers and the public to encourage nimble responses to the challenges climate change pose,” Ganguli said.

The new research, led by Prakash Jha, UC Agriculture and Natural Resources assistant project scientist based at UC Merced, compared pest populations in recent and future climates. The scientists used temperature projections from the latest generations of scientific models to predict the potential impact of climate change on codling moth (Cydia pomonella), peach twig borer (Anarsia lineatella) and oriental fruit moth (Grapholita molesta). Before using the model, the model predictions were verified using field data of these insect pests from various parts of the Central Valley.

The peach twig borer damages peaches. Photo by Jack Kelly Clark

The UC study revealed that due to increases in temperature, these insects are expected to appear up to 28 days earlier in the spring and the time between generations is expected to shorten by up to 19 days. The changes may be gradual, but the study predicts that we may see up to a half-generation of these pests added within the next 20 to 30 years.

The increase in these pest populations poses a serious threat for future pest management, which would subsequently affect the state's economy and employment related to specialty crops, warns Rijal.

“Codling moth is the primary pest of California's walnuts, which occupies over 365,000 acres,” Rijal said. “Similarly, peach twig borer and oriental fruit moth are two major economic pests of peaches. Growers must control almost every generation of these pests to protect the fruit.

“Additional generations of these pests within the same growing season will likely increase crop damage. It certainly increases the number of sprays needed to control these pests, increasing the production cost for growers. Plus, more use of insecticides has consequences for beneficial insects and the environment.”

Codling moth larvae inside a walnut. Photo by Jack Kelly Clark

Growers may need to adapt their pest management strategies to address the impact of climate change on these pests. 

For years, the UC Integrated Pest Management guidelines have suggested putting oriental fruit moth traps out in peach orchards by Feb. 15 in the San Joaquin Valley and Feb. 20 in the Sacramento Valley.

“In the last seven years, likely due to warmer winter, as suggested in this study, we observed the beginning of the moth's activity in traps (also called biofix) as early as Feb. 14,” Rijal said, “meaning that the trap placement date must move earlier to capture the first moth activity. We are revising the guidelines to change the trap placement date to Feb. 7 for the entire Central Valley.”

Developing a holistic climate-smart pest management strategy will build resilience, Jha said. This approach combines pest control with prevention and reduction, such as planting pest-resistant crop varieties, sanitizing the orchards during the winter, harvesting early to avoid later pest generation infestation, using biological control such as natural enemies, and deploying mating disruption techniques.

“More importantly, adoption of pest forecasting – including the long-term prediction and short-term potential outbreak, pest-scouting and early detection – will be essential to combat the growing threat posed by these pests,” Jha said. 

Research will be crucial to provide growers support and guidance about the latest developments in pest management and how to adapt their practices.  

“Climate change impacts on pests and resulting impacts on agricultural production are significant but not often researched or quantified,” said Tapan Pathak, UC Cooperative Extension specialist in climate adaptation in agriculture based at UC Merced.

“Information from this research will not only help farmers to understand impacts for strategic planning, but also will inform the agricultural industry to invest in making varieties more resilient to these damaging agricultural pests,” Pathak added. “We will use this information to update the CalAgroClimate tool, which informs farmers on the progress of these pests during the season so that they can take steps for effective pest management.”

Ganguli added the partnership between the University of California and the California Climate Hub embodies the goal of this funding program.

“The incorporation of this research into the existing CalAgroClimate decision support tool accelerates the ability of this information to be publicly used in the development of appropriate pest management or adaptation strategies,” she said.

In addition to Jha, Rijal and Pathak, the study was co-authored by Ning Zhang, Lauren E. Parker and Steven Ostoja of UC Davis Institute of the Environment and U.S. Department of Agriculture California Climate Hub.

The article “Climate change impacts on insect pests for high value specialty crops in California” can be accessed for free online at https://doi.org/10.1016/j.scitotenv.2023.167605.  

Dec. 8, 2023: This story was updated to add comments by NIFA National Program Leader Amy Ganguli.

 

 

 

Posted on Wednesday, October 25, 2023 at 11:23 AM
Tags: almonds (55), climate chance (1), peaches (21), pest management (5), walnuts (25)
Focus Area Tags: Agriculture

Winter atmospheric rivers gave pathogens, diseases path to infect crops

Outbreaks similar to El Niño-influenced issues of the 1990s

The wave of atmospheric rivers that swept across the state this winter has created the right conditions for plant pathogens that haven't been seen for decades in California. University of California, Davis, plant pathologist Florent “Flo” Trouillas is getting more calls from growers and farm advisors concerned about potential crop damage.

“Generally, whenever you have rain events, you're going to have problems,” said Trouillas, a Cooperative Extension specialist who is based at the Kearney Agricultural Research and Extension Center in Parlier. “In wet years we get really busy because most pathogens need and like water.”

Trouillas is like a disease detective. He splits his time between the field and the lab, working to diagnose pathogens, diseases and other ailments that strike fruit and nut crops such as almonds, cherries, olives and pistachios.

UC Cooperative Extension specialist Florent Trouillas examines a cherry tree in Lodi for potential pathogens. Photo by Jael Mackendorf, UC Davis

On a recent visit to an almond orchard near Fresno, Trouillas joined Mae Culumber, a nut crops farm advisor for UC Cooperative Extension Fresno County. A few weeks earlier, the two had walked the orchard, taking note of the base of some trees that had gumming — a thick, jelly-looking substance indicating a pathogen had taken hold.

“A lot of what Florent is doing is trying to assess patterns on a landscape,” Culumber said. “Sometimes things may look like they are one thing, but it could be another problem.”

When the two returned weeks later, the amber-colored gumming had moved into the canopy, looking like gumballs stuck to branches, some of which were already dead. “It's getting out of control from before,” Trouillas says. “This branch was killed. This is widespread.”

From the field to the lab

Lab testing confirmed what Trouillas believed was the culprit: Phytophthora syringae, a pathogen that can affect almond crops but is rarely seen in California. If it is found, generally the site of infection are wounds caused by pruning, but that is not the case here, where the infection began in the canopy at twigs, or small branches.

It is a threat to a key crop, which according to the California Department of Food and Agriculture, generates $5 billion annually. The last time Phytophthora syringae hit California was in the 1990s after a series of El Niño-influenced storms. Trouillas, who has a photographic memory, remembered reading about it in an old manual.

An almond tree near Fresno infected with the pathogen Phytophthora syringae. The pathogen is usually found in tree roots but intense storms created the right conditions for the pathogen to "swim" up trunks. Photo by Emily C. Dooley, UC Davis

“It's rare for California and one that we see mostly following atmospheric rivers,” he says.

“The disease will only happen following these extremely wet winters.”

Phytophthora is soilborne, mostly found in tree roots, and doesn't generally spread up into branches. But the intense storms created the right conditions for the pathogen to “swim” up trunks as winds blew spores into the air and rain dropped them back down into the canopy, Trouillas said.

Some of the trees in this orchard will die; others can be saved by pruning infected branches and applying a recommended fungicide, he said.

Identification, diagnosis, education

Trouillas is one of more than 50 Cooperative Extension specialists at UC Davis and each is charged with identifying problems and developing solutions for those issues in support of agriculture, the ecosystem and communities throughout the state.

In his role, Trouillas focuses not only on pathology and research but also on educating growers, nursery staff, pest control advisers and others in agriculture about ways to manage potential threats and how to prevent crop damage.

Mohamed Nouri, an orchard systems advisor for UC Cooperative Extension San Joaquin County, and UC Davis plant pathologist Florent Trouillas gather samples in a cherry orchard in Lodi showing signs of bacterial canker. Photo by Jael Mackendorf, UC Davis

“His role is very crucial,” said Mohammad Yaghmour, an orchard systems advisor for UC Cooperative Extension Kern County. “He's not only on this mission to educate growers but he's also a source of education for us.”

Trouillas typically conducts one or two site visits a week, usually after a farm advisor reaches out about a problem they can't solve on their own.

“This allows us to be at the forefront of disease detections in California,” he said.

He likens these visits to house calls a doctor would make, only to fields instead. And one of those calls recently took him to a cherry orchard in Lodi.

“These guys help me quite a bit,” said Andrew Vignolo, a pest control adviser with Wilbur-Ellis who asked for a consult. “I bug them a lot.”

The visit starts like any consult in a doctor's office, only the questions come fast as they walk around the Lodi orchard where branches are dying, there is gumming and the trees appear stressed. Some look to be sunburned from exposure. Old pruning wounds show cankers, indicating that past disease treatments didn't get rid of whatever was affecting the trees.

Trouillas asks about the cultivar of the trees because some varieties are more susceptible to pests or diseases. He focuses on stress because that opens the door to disease.

Do they prune in the dormant winter months or in summer when pathogens are more prevalent? Does the soil get tested? How old are the trees? What about nutrition?

“I'm trying to figure out how they got infected so bad,” Trouillas said, walking the orchard. “Bacterial canker is a very mysterious disease.”

He thinks it might be a bacterial canker disease and shaves some bark to take to the lab for testing. He wants to come back next winter to take some samples to see where the pathogen is overwintering.

“We'll know in a few weeks if we have a fighting chance,” Vignolo said.

Be it Lodi, Fresno or elsewhere in the state, Trouillas focuses on local conditions. But what is learned in one field can be passed on to others, providing early warnings or advice for those in similar situations. “All these efforts at collaboration, from the field, to the lab, going through research projects, there's only one goal here — to help the farmers of California.”

Posted on Monday, May 15, 2023 at 1:15 PM
  • Author: Emily C. Dooley, UC Davis
Focus Area Tags: Agriculture, Environment, Food

Climate change may reduce frost damage to orchard crops

Extreme cold can kill almond buds and flowers. Running sprinklers can warm the orchard to prevent frost damage. Photo by Allen Vizcarra

Irrigation water may ice some flowers, but help protect flowers in the upper canopy from frost damage. Photo by Allen Vizcarra

CalAgroClimate web tools help farmers prepare for frost events

A cold snap damaged almond blossoms across the Central Valley, resulting in more than $44 million in crop insurance claimsin late February 2018. A multi-day frost event wiped out roughly 75% of California's citrus crop and severely damaged avocados in January 2007. Frost can damage crops, impact growers' bottom lines and drive up food prices for consumers. With advance notice, farmers may be able to use heaters, wind machines, irrigation and other tactics to lessen some of the impacts of cold weather, such as damaging near-ripe citrus fruit or killing the bloom in almonds.  

CalAgroClimate is a new farmer-focused website that can help growers anticipate weather-related risks and make plans for taking defensive action. Growers and crop consultants can use CalAgroClimate's crop and location-specific tools and resources to help prepare for upcoming frost events. The website's tools can also support on-farm decisions for managing heat, crop development and pests. 

Future holds less frost

The risk of frost damage to crops and the need to prepare for that risk is top-of-mind for many farmers today, but will it always be so? To examine what climate change might mean for future frost risk, researchers at UC Davis, UC ANR and the USDA California Climate Hub conducted a study examining the incidence of temperatures below multiple “frost thresholds” during the months of critical development phases for three frost-sensitive California crops: almonds, avocados and navel oranges.

Severely frozen avocados may show brown water-soaked spots in the skin, gray areas in the flesh and may even crack or split. Frost-damaged fruit is unmarketable and will drop from the tree. Photo by Mary Lu Arpaia

The researchers found that even during the coldest winters and springs, the incidence of frost exposure declined under projected mid-21st century climate conditions by more than 50% for almonds and oranges, and by more than 75% for avocados. While farmers in 2050 will not find frost risk to completely be a worry of climates past, they will not have to contend with the same frost concerns that farmers face today.

Frost-damaged citrus
Beyond the obvious benefits of reduced risk of crop damages, additional benefits of reduced frost exposure include lower water use and energy costs associated with mitigation actions. Irrigation is a primary means of protecting crops from frost temperatures, and with fewer hours below freezing that means fewer hours of running water and using pumps. The authors of the future frost exposure study showed that growers may collectively save tens of thousands of acre feet of water and enjoy millions of dollars in energy savings.

Few aspects of climate change are considered “positives,” and although the warming winters and springs that result in reduced frost temperatures could also come with increased pest pressure, reduced chill accumulation and other challenges, the reduction in frost exposure is a silver lining.

However, until this frost-free future arrives, growers still need to be prepared to protect their orchards from frost. To assess frost risk for the next seven days for your location, check out the new interactive Frost Advisory Tool at CalAgroClimate.org.

Posted on Monday, January 23, 2023 at 1:20 PM
  • Author: Lauren E. Parker, USDA Climate Hub
  • Author: Tapan Pathak, UC Cooperative Extension specialist
Tags: almonds (55), avocados (14), CalAgroClimate (2), citrus (34), climate change (136), Tapan Pathak (17)
Focus Area Tags: Agriculture

Five questions with food safety expert, new AAAS Fellow Linda Harris

Linda J. Harris will be inducted as a member of the 2021 class of American Association for the Advancement of Science Fellows during the AAAS annual meeting. Photos courtesy of Linda J. Harris

Professor of Cooperative Extension shares career story, appreciation for UC Davis

After growing up in northern British Columbia, in a remote smelter town called Kitimat (“an 8-hour drive from the nearest McDonald's”), University of California Professor of Cooperative Extension Linda J. Harris embarked on an academic journey that crisscrossed North America and eventually led to her election as a Fellow of the American Association for the Advancement of Science.

AAAS, the world's largest multidisciplinary scientific society and publisher of the journal Science, recently announced the election of its 2021 class, which will be inducted during its annual meeting, Feb. 17-20.

In addition to Harris – a faculty member in UC Davis' Department of Food Science and Technology – four other UC Agriculture and Natural Resources affiliates will be inducted: Helene Dillard, dean of the UC Davis College of Agricultural and Environmental Sciences; Kathryn Uhrich, dean of the UC Riverside College of Natural and Agricultural Sciences; and UC Berkeley Professors Rodrigo Almeida and Paolo D'Odorico.

Harris, a Certified Food Scientist, recently shared her thoughts on the value of extension work, her contributions to the field, UC Davis' support for women in academia, and the arc of her career journey.

Harris was elected as an AAAS Fellow for her contributions to the field of food safety microbiology, especially related to control of Salmonella.

How did you get your start in food science and microbiology?

I was interested in science at an early age. As an undergraduate student at the University of Victoria in Victoria, B.C., I enrolled in biochemistry at the suggestion of my high school biology teacher. In my second year, I switched to the University of Alberta in Edmonton, Alberta and decided to review the course catalog – a paper version! When I got to the section on Food Science, the applied nature of the field just sounded right and I never looked back.

However, I didn't do particularly well in microbiology as an undergraduate student – too much memorization for me. At the end of my B.S. I was ready for a job in the food industry and took the very first job I was offered – ironically enough as a dairy microbiologist in a quality control lab. Thankfully, that job opened my eyes to the possibilities in microbiology. What was memorization turned into something I learned through doing and I was hooked.

Two years later, I was ready to go back to school and contacted a professor of food safety microbiology at the University of Alberta who fortunately had funding for me. During my M.S. degree in food microbiology, he encouraged me to pursue the Ph.D. – which was not something I had ever considered – and that led me to leave Canada and head to North Carolina State University and a Ph.D. in microbiology in the Food Science Department, where I worked on a project related to the fermentation of sauerkraut.

I did have one publication related to food safety during my time at NC State, and when I took my first faculty position back in Canada [University of Guelph in Ontario] I continued to work in food safety, mostly with meat and meat products.

I am so glad that I saw the advertisement for my current position and that I followed my instincts to apply for the job. The opportunities to grow professionally and to work in the food safety area at UC Davis, within the Cooperative Extension network in California, and with collaborators across the U.S., and around the world, have been enormous, and I am extremely grateful for the path that led me here.

Growing up in Kitimat, British Columbia, Harris developed a love for science at a young age.

February 11 is the United Nations-designated “International Day of Women and Girls in Science.” How has UC Davis supported women in your scientific field?

My career in STEM [science, technology, engineering and math] has been very rewarding and many of the gender barriers I faced early on have been addressed. I feel very fortunate to have landed at UC Davis and I am thankful that there is a long history of addressing these barriers at this institution.

When I was hired in 1996, the Department of Food Science and Technology was about 25% women and both the department chair and dean of the college were women. I had never been in a department or college with so many women faculty, including in positions of leadership. It was a very important consideration in my move. Today our department is 50% women and I proudly served for five years as the second woman department chair, from 2016 to 2021.

As a first-generation university graduate raised by a single mother, you have a unique perspective in encouraging young people on their path toward a STEM career. What advice do you have for them?

To those contemplating a career in STEM, I would say: be open to new opportunities and adventures – you never know where they may lead you. Get involved in leadership in any capacity you can from student organizations or around other things that interest you. Skills that you learn with these types of activities will be invaluable to your career.

I am very much an introvert and had to work hard to overcome my fear of public speaking. In addition to leadership roles in student clubs, I joined Toast Masters while working on my Ph.D. These activities had a huge impact on building my confidence and helped influence my career choices.

Through her work as a Cooperative Extension specialist, Harris has been able to understand firsthand the food-safety needs across California.

In the AAAS Fellows announcement, it says you were elected for “contributions to the field of food safety microbiology, especially related to control of Salmonella and other pathogens in low-moisture foods and fresh produce.” Is that your proudest achievement in the field?

I am most proud of the work described by that short statement especially as it applies to California-grown commodities. I would say that my laboratory is best known for work with the tree nut industry – almonds, pistachios and walnuts, as well as a range of types of fresh produce grown in this state.

My laboratory has worked to understand behavior, movement, prevalence, and especially control of foodborne pathogens like Salmonella during production in the field through harvest and postharvest handling all the way through to consumer practices.

I have been fortunate to have many terrific state, national and international collaborators and an outstanding group of people working in my laboratory as we set the foundation for some of the food safety research in tree nuts and produce. It has been most gratifying to watch the significant growth in these fields of investigation, especially with a new generation of scientists that span the country and beyond.

Another “hat” you wear is UC Cooperative Extension specialist. How have you contributed to food safety knowledge and practices in our communities?

I think you will see that my “hats” are not that different. The research from my laboratory has provided the foundation for several commodity-based, food-safety risk assessments – for almonds, pistachios, and walnuts. And these, in turn, have been used in support of regulations or helped guide implementation of safer food industry practices. Our research has also informed several publications aimed at consumer handling of fresh fruits and vegetables and has been cited in regulations pertaining to fresh produce safety. It is gratifying to see our research being used.

My research and extension work are very integrated. One feeds the other. Because I have been able to interact with stakeholders (especially integral to my position as a Cooperative Extension specialist), I have been able to understand firsthand some of the pressing food-safety issues and challenges in California. These stakeholder interactions have largely formed the basis for most of my research and extension grant proposals over the years. The collaborations that have resulted from extension activities have opened doors and access to many unique opportunities for sample collection and research exploration.

Posted on Thursday, February 10, 2022 at 8:46 AM
Tags: AAAS (1), almonds (55), Fellow (1), Food Safety (89), Food science and technology (2), Linda J. Harris (1), pistachios (18), Q&A (1), Salmonella (12), tree nuts (3), UC Davis (92), walnuts (25)
Focus Area Tags: Agriculture, Food, Health

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