Posts Tagged: food
Date palm irrigation research provides economic, environmental benefits
Historically, date palms are grown along riverbeds or in areas with groundwater because they require an abundance of water to produce a good crop. Unlike lettuce or table grapes, date palms are deceptive in that they do not immediately wilt if underwatered. Eventually, however, the lack of water hurts yields and fruit quality.
The default for date growers is to apply excessive water, but doing so is neither economically nor environmentally sound. To help growers, Ali Montazar, UC Cooperative Extension irrigation and water management advisor for Imperial, Riverside and San Diego counties, has developed knowledge that enables growers in the region to establish irrigation guidelines they can use with confidence.
“Water issues in California's desert are very different than in the Central Valley,” said Montazar. “There is no groundwater to recharge so growers in the desert only have the Colorado River.”
Since 2019, Montazar has been focused on irrigation management for date palms in the Coachella Valley, the largest producer of dates in the United States. Montazar's research identifies how much water is needed for the crop and the best water delivery method according to location, soil type and conditions, and date cultivars.
“Dates require a lot of heat and light, which is why they do well in the desert. But they also need a fair amount of irrigation,” said Robert Krueger, a U.S. Department of Agriculture horticulturist and Montazar's co-author of a paper on date palm irrigation management.
Much of what we know about date palm production comes from the Middle East, which has a climate similar to the low desert of California. “That information is from many, many years ago though,” explained Montazar, whose research shows that drip irrigation cannot be the only form of irrigation for date palms.
“Ali is the first to really look at micro-sprinklers and flood irrigation for date palms,” said Krueger, adding that the other advantage of Montazar's research is that it prepares growers for production during times of reduced water supply.
Albert Keck, president of Hadley Date Gardens, Inc. and chairman of the California Date Commission, described Montazar's research efforts as “subtle yet incredible and profound,” adding that his findings not only benefit other farmers but also cities relying on water from the Colorado River.
Keck, one of the largest date growers in California, is well aware of how disruptive, expensive and time-consuming irrigation for date palms can be. Montazar has enabled growers like Keck to irrigate less without sacrificing yield or quality.
“Ali might save us a tiny percentage of the amount of water we're using. It might be a 5 or 10% savings. It doesn't seem like much, but it's an incremental improvement in efficiency,” said Keck. “And if you add all of these improvements up, say, along the U.S. Southwest, then that has a pretty profound impact.”
Montazar recommends that date growers in his region use a combination of drip and two to three flood irrigation events to manage salinity levels derived from the Colorado River. “We cannot maintain salinity issues over time if we're only relying on drip irrigation in date palms,” explained Montazar.
Flood irrigation pushes the salts below the root zone, when they would otherwise build up within the root zone preventing efficient water uptake. It also aids in refilling soil profiles quickly and more effectively since drip has a lower capacity of delivering sufficient water.
“Growers know what they need to water their crop within a broader parameter. But Ali has narrowed that window and helped us become more precise with our irrigation,” Keck said. “There's still room for improvement but we're spending less money, wasting less time and using less water now, and we're still getting the same positive results.”
Currently,Montazar is collaborating with the California Date Commission on developing guidelines for best irrigation management practices in the desert for date palms, which should be available by the end of 2023. These guidelines are based on a four-year data set from six monitoring stations and extensive soil and plant samples from commercial fields located in theCoachella Valley, Imperial Valley and near Yuma, Arizona. Additionally, Montazar is working to quantify how water conservation impacts growers economically.
“Growers from United Arab Emirates, Egypt, Tunisia and Mexico have already reached out asking for this information,” Montazar said, while reflecting on a presentation he made to a group of international date growers in Mexico late last year.
To read the paper on date palm irrigation, published in MDPI's Water journal, visit: https://www.mdpi.com/2073-4441/12/8/2253.
Nearly 70% of private label avocado oil rancid or mixed with other oils
Researchers identify key markers to help professional retail buyers choose authentic products
Avocado oil has become a popular choice for many people in recent years because of its heart-healthy benefits and versatility in cooking. However, not all avocado oil products on store shelves are created equal. Some products are labeled as “pure” avocado oil when they contain other oils or additives. No enforceable standards defining the chemical and physical characteristics of avocado oil exist yet.
Researchers at the University of California, Davis, analyzed samples of 36 private label avocado oil products and graded them based on quality and purity. Private label products are made by a third-party processor and sold under a grocery store or retailer brand label. Their findings, published in the journal Food Control, show that 31% of the samples tested were pure, and 36% were of advertised quality. Quality refers to whether the oil is fresh or has gone bad due to aging, heat or light exposure. For purity, researchers measured fatty acids, sterols and other components that differentiate avocado oil from other oils.
The study included oils purchased from 19 retailers in the U.S. and Canada with various price points. They found that lower-priced oils were more likely to be tainted with other oils.
“We found that low-cost products indicate a higher probability for adulteration, but high cost didn't guarantee purity or quality,” said Selina Wang, associate professor of Cooperative Extension in the Department of Food Science and Technology. She and Hilary Green, a postdoctoral researcher at UC Davis, co-authored the paper.
Researchers also identified certain chemical markers in avocado oil that professional retail buyers can use to make more informed decisions when it comes to choosing suppliers. This way, consumers can feel confident about the products they buy.
This is the second comprehensive study conducted by UC Davis researchers on the quality of avocado oil sold in the U.S. The first study released in 2020 found that many of the test samples were of poor quality, mislabeled or adulterated with other oils.
“This study demonstrates that although progress is being made in standard development since our first market study in 2020, there are still issues with purity in avocado oil and these issues extend significantly into private label oils,” Wang said.
Avocado oil standards
Since the release of the first UC Davis study, Wang said there's been a coordinated effort by researchers, industry leaders and government agencies to establish enforceable standards. The Avocado Oil Expert Group was formed in collaboration with the American Oil Chemists' Society to discuss potential standards and future research projects.
Wang's research group has been studying how natural factors like different types of avocados, harvest times, geographic origins and processing methods could affect the chemical composition of avocado oil. They want to create standards that will accommodate natural variations while detecting any adulterations.
Wang hopes that the study's findings will contribute to the establishment of standards that benefit both consumers and avocado oil producers who want to compete in a fair market.
“I'm very optimistic for the future of the avocado oil industry,” Wang said. “It's a high-value product with high consumer demand, similar to what I saw with olive oil 10 years ago. Olive oil quality and purity have improved significantly, which is where I see avocado oil going, if we can establish fair standards and eliminate fraudulent products.”
/h3>/h3>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.
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.
“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.
“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.”
/h3>/h3>/h3>Indigenous science key to adapting to climate change
UC Berkeley and Karuk Tribe use Indigenous and western science to cultivate resilient food systems under changing climate conditions.
To adapt to climate change, Karuk Tribe members identified the importance of monitoring climate stress on plant species and actively managing and restoring healthy ecosystem processes to increase the consistency and quality of their food harvests, according to a new report. The Karuk Tribe's Aboriginal Territory encompasses over a million acres in the Klamath Basin in Northern California and Southern Oregon.
The Karuk Tribe-UC Berkeley Collaborative has released findings from its four-year collaborative research in their report “Karuk Agroecosystem Resilience and Cultural Foods and Fibers Revitalization Initiative: xúus nu'éethti – we are caring for it.”
To assess climate-change impacts on cultural-use plants and their habitats and to develop strategies and tools for long-term monitoring, this project integrated Indigenous and western science perspectives.
“Understanding the breadth and intensity of climate change with regard to our cultural resources is key to developing adequate response plans,” said Karuk cultural practitioner and project co-lead Lisa Morehead-Hillman. “Without healthy stands (of trees), our cultural practices suffer. We all suffer.”
The report authors lay out specific place-based management and monitoring actions that will enhance the resilience of cultural focal species and habitats to climate change, climate variability and management threats.
To support the resilience of Indigenous cultural agroecosystems and cultural food and fiber species, as well as strengthening Indigenous food sovereignty now and into the future, the authors recommend the following management, policy, research and institutional actions:
• Supporting Karuk Tribal natural resource, data and knowledge sovereignty through appropriate engagement and Tribal oversight.
• Investing in Tribal management infrastructure and workforce development to support culturally appropriate, place-based job opportunities for Tribal members and descendants.
• Supporting co-management and family-based stewardship of cultural use plants and habitats on Karuk Aboriginal lands.
• Investing in and supporting the re-acquisition of Karuk Aboriginal lands to build back the Tribal land base and restore habitats and ecosystems.
• Funding research, monitoring, and educational opportunities that can support youth leadership development, job creation, agroecosystem resilience, and food sovereignty in Karuk Aboriginal Territory.
This research builds on the findings from a five-year Karuk Tribe-UC Berkeley Collaborative food security project (2012-2018), which found that 92% of all Tribal households in the Klamath River Basin experienced some level of food insecurity, and that having access to cultural foods was a strong predictor of food security, yet only 7% of all Tribal households had access to good quality cultural foods at all times.
“This project applies what we learned from tribal members about food insecurity and climate and land management threats to cultural foods to the landscape level, co-creating methods and tools with our Karuk colleagues to assess and restore the health, quality and abundance of cultural foods and fibers to promote food security and eco-cultural resilience,” said Jennifer Sowerwine, lead UC Berkeley collaborator and associate professor of Cooperative Extension.
Research objectives centered around the “Agroecosystem Condition Assessment,” in which UC Berkeley and Karuk researchers and cultural practitioners assessed the health, quality and yield of 20 cultural-use focal plants prioritized by the Karuk Tribe, such as tanoak acorns, evergreen huckleberry, bear grass and hazel, as well as the condition of their habitats.
“This project demonstrates the benefits of working with a diverse research partnership in the co-production of climate science using blended Indigenous and Western research and monitoring methods,” said project collaborator Frank Lake, research ecologist and USDA Forest Service Pacific Southwest tribal liaison. “This project exemplifies recent federal directives and initiatives to support tribes for climate adaptation, forest restoration and eco-cultural revitalization.”
The overall quality and condition of most of the focal species found in the research plots and patches reflect both the devastating impact of colonial land-management practices – including timber harvest, fire exclusion and mining – as well as clear evidence of climate stress such as aborted fruit, early die back and poor-quality product. Forced exclusion of cultural management is reflected in encroachment of invasive species, inappropriate canopy cover and poor-quality harvests impacting both human and animal access to these important plant resources.
“This work done among Indigenous knowledge holders and academia is paramount to developing and sustaining a well-trained workforce for the future,” said Bill Tripp, director of the Karuk Tribe Department of Natural Resources and project co-lead. “We have a long way to go in realizing cultural relevancy in addressing the systemic injustices that plague our people, accelerate climate change, and work against ecosystem process and function.”
Based on research findings informed by the deep insights of Karuk natural resources managers, Karuk elders and cultural practitioners, the report outlines recommendations for restoring key habitats and revitalizing culturally significant species to enhance agroecological resilience in Karuk Aboriginal lands, which are concurrently administered, managed and occupied by U.S. Forest Service and private landowners.
Kathy McCovey, a Karuk cultural practitioner, archaeologist, forest ecologist and project collaborator, explained the cultural significance of the project:
“Through this project, we are learning how to reconnect with place,” McCovey said. “In learning about and tending these areas, we are tending our family gardens. It's all about people in place. Working on this project, we are working to bring these places back to life. We're rediscovering their Karuk names and how those names signal traditional uses of plants in those places. That way we can reconnect with the places our families come from”.
“The whole river system is full of knowledge,” she elaborated. “It's a crucial time for the Karuk people to tend these areas and learn how to take care of them. This community has knowledge that's developed and evolved with these lands and we have a responsibility to support the plants in these areas. We had our land stolen out from under us, but we still live here, we still know how to tend and gather plants, we still have our knowledge and our ceremonies. We still have the ability to go out and gather from the land. We still know how to take care of this place. We take care of the land and it takes care of us.”
This project serves as an example of how university and federal agency researchers can partner with California tribes to lift up Indigenous knowledge, which can help all involved to better understand and develop solutions to the climate crisis and its effects on California's landscapes and biodiversity, especially on species of cultural significance to Indigenous communities.
Funding for the project was provided by a grant from the USDA NIFA Agriculture and Food Research Initiative Resilient Agroecosystems under Changing Climate Challenge Area.
Download the free report at the Karuk-Berkeley Collaborative website: https://nature.berkeley.edu/karuk-collaborative/wp-content/uploads/2023/03/Karuk-Resilience-Report_Smallest-file-size.pdf
/h3>Lambs grazing on pastures after wildfire show no significant adverse effects
Hopland REC turns 2018 River Fire devastation into research opportunity
The destructiveness of wildfire flames is easy to see, but dangers may lurk in the ashes they leave behind. A group of UC Davis scientists studied lambs at the UC Hopland Research and Extension Center, investigating whether pastures regrown after a wildfire cause toxic metal residues in grazing animals. The results, published in California Agriculture journal, showed that grazing on regrown pastures did not significantly alter the metal content of the lambs' meat and wool. That's good news for ranchers and consumers from a food safety perspective.
In 2018, the River Fire burned six miles north of Hopland, scorching two-thirds of the land at Hopland REC, including areas in its sheep station. Since Hopland REC conducts ecological and agricultural research, they had data and some meat samples from the sheep flock that lived on site before the River Fire occurred.
“A bunch of researchers came together to brainstorm how we could take advantage of this unfortunate event,” said Sarah Depenbrock, assistant professor and agronomist in the Medicine and Epidemiology department of UC Davis School of Veterinary Medicine.
Burning has played a role in agricultural processes for many years, but wildfires in California are creating a new fire landscape that interests researchers like Depenbrock. “The problem, now, is that these big wildfires probably interact with agricultural land differently than routine prescribed burns,” she said.
Large, older plants on lands that have not recently burned may contain high concentrations of metals, sequestered over years of growth. Mercury is an example of a potentially dangerous metal that can be sequestered in living things over time. These metals may be distributed in ash after the vegetation burns so the scientists examined lambs that had grazed on Hopland REC's recently burned pastures, during the first plant regrowth.
Uncertain results raise more questions
The researchers compared meat from lambs that grazed on regrown pastures in 2019, after the River Fire, to frozen meat samples that were collected the year before the fire. Lead, mercury, arsenic, molybdenum, cadmium, beryllium, cobalt and nickel were not detected in any animal samples. There were, however, a few (3 out of 26) samples that tested positive for the non-essential (potentially toxic heavy metals) chromium and thallium in the group grazing after the fire.
Due to the small number of samples testing positive, researchers could not determine statistically if this contamination was associated with grazing the burn regrowth. The concentrations of chromium and thallium found may or may not be potentially toxic, depending on the specific forms and how much meat a person consumes.
Another aspect of the study included testing lambs' wool to determine if it is a good method of judging the mineral content of its meat. “In general, we learned that it wasn't well-correlated with most meat metal content of interest, which is worth knowing. However, because we did not identify many of the non-essential metals of particular toxologic concern, such as lead or mercury, in any animal samples we could not determine if testing wool would be useful for those metals, as they are in other species,” said Depenbrock. She also notes that the wool from animals whose meat tested positive for chromium and thallium, did not test positive for these metals in their wool.
As the challenges in managing wildfires persist, so does the risk of contamination of food products stemming from grazing livestock.
“We didn't get striking evidence that tells us, when there's a fire, it means everything is contaminated with heavy metals,” said Depenbrock. “But it does raise the question that maybe we should be doing a little bit of surveillance to see if this is spurious or common. And we should be finding a way to screen grazing herds.”
Recommendations to manage copper concerns
“It's a very small study, but it was quite interesting to find that copper was actually lower in the postfire grazing group, which makes me wonder,” Depenbrock said.
Diseases associated with copper deficiency are a major concern in sheep. For example, congenital swayback can result in stillbirth or an animal's inability to stand on its own due to incurable changes to the spinal cord. Other adverse effects include reduced growth rate, anemia, wool defects and fiber depigmentation, and osteoporosis with higher risk of spontaneous fractures. Copper excess can also cause serious and sometimes fatal disease.
Many of the forage sources, grazing areas and rangelands in California are copper deficient, while some feed sources have excess copper. Screening and monitoring livestock herds for trace minerals including copper is crucial.
To test for copper, she advises livestock owners to obtain mineral concentrations from the organs of euthanized or dead animals. Samples from the liver and kidney are the most valuable organs to identify a potential problem in the herd. UC Davis Veterinary Medicine's California Animal Health and Food Safety (CAHFS) labs do this testing routinely.
Second, monitor and record mineral supplementation and, third, maintain updated health records to make informed decisions regarding supplementation based on a herd or flock's known problems. For example, if a producer is not accustomed to supplementing copper, Depenbrock highly recommends working with a veterinarian to start out (as there are numerous copper supplement products of varying concentration on the market), to determine a testing or screening plan, and review health records for problems potentially associated with copper.
To read the full text of the study, visit https://calag.ucanr.edu/Archive/?article=ca.2022a0016.
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