Facebook
X (Twitter)
Reddit
Pinterest
Tumblr
Delicious
LinkedIn
StumbleUpon
Posts Tagged: food
Almond crop yields threatened by disease new to California
Detection of fungus causing red leaf blotch spurs call for grower vigilance
Symptoms of red leaf blotch (RLB), a plant disease caused by the fungus Polystigma amygdalinum, have been observed for the first time in California across the Northern San Joaquin Valley.
Molecular DNA testing by the laboratory of Florent Trouillas, University of California Cooperative Extension fruit and nut crop pathology specialist, has confirmed the detection of P. amygdalinum. Formal pest confirmation by the California Department of Food and Agriculture is pending.
The disease, named for the characteristic orange-to-dark red blotches that appear on infected leaves, is typically nonlethal for trees but has been a long-standing problem for almond-growing regions across the Mediterranean. Causing trees to lose their leaves prematurely, the fungal pathogen can significantly diminish crop yields in the current year and the next.
“It is one of the most severe diseases of almonds for Spain and the Middle East,” said Trouillas, who co-authored an explanatory article on the UCCE San Joaquin Valley Trees and Vines blog.
With symptomatic trees seen in multiple orchards across Madera, Merced, San Joaquin and Stanislaus counties, Trouillas said RLB is already “somewhat widespread.”
“From the first observations so far, it seems like it affects some of the most-planted cultivars, like Nonpareil and Monterey,” he added. “We've observed it in a diversity of cultivars already.”
UC Cooperative Extension specialist urges taking preventive measures
According to Trouillas, RLB caused by P. amygdalinum is “highly specific” to almond trees, and generally only affects their leaves. Infection typically happens at petal fall, when small leaflets are first emerging and most susceptible to disease. After the pathogen's latent period of about 35 to 40 days, the first symptoms appear – small, pale-yellow spots on both sides of the leaves.
Those blotches become yellow-orange and then reddish-brown in the advanced stages of the disease during June and July. Now, with RLB symptoms becoming more prominent, Trouillas and UC Cooperative Extension advisors across the Central Valley have seen an uptick in calls.
“PCAs [pest control advisers] have been confused because they've never seen anything like this,” said Trouillas, noting that the yellow-orange-red blotches are symptoms unique to RLB and cannot be confused with other known almond diseases.
Applying fungicides after RLB symptoms appear is ineffective, Trouillas said. The best thing growers can do at this point is to report symptomatic trees to researchers so they can track the prevalence and distribution of the disease.
Growers who see signs of this new disease in their orchard should contact their local UC Cooperative Extension farm advisor.
Preventive measures are the best way to manage RLB, Trouillas said. He urges concerned growers to think ahead to next winter/spring and plan for fungicide applications at petal fall and – if rains persist – also at two weeks and five weeks after petal fall. Fortunately, those are the same three key timings for managing other diseases, like shot hole and almond anthracnose.
“Because RLB is something that is introduced and potentially aggressive, it will be important for growers to keep that in mind next year and be on schedule for next year's spraying program,” Trouillas said.
Additional information on RLB can be found at https://www.sjvtandv.com/blog/first-detection-of-red-leaf-blotch-a-new-disease-of-almond-in-california.
Diagnosing herbicide problems takes detective work
Field day offers examples, tips for solving the mystery
A grower applies an herbicide to his tomato plants, or thinks a neighbor's treatment is drifting over her almond trees. A short time later, the leaves start to bleach or shrivel. Was it the herbicide? Or maybe water stress? Soil nutrients? Perhaps an insect?
Figuring out the causes of crop problems takes detective work, and like solving any mystery, it starts with knowing the signs, gathering evidence and asking questions.
The Diagnosing Herbicide Symptoms field day at UC Davis was an opportunity to see, up close, the shriveled cotton, scorched corn and dying sunflowers that can result when herbicides are applied incorrectly. Using the right herbicide – in the right proportion, at the right time and in the right field – can make the difference between a thriving crop and a financial loss.
A top take-away to avoid problems: “Don't do stuff at night!” laughed Becky Wheeler-Dykes, a UC Cooperative Extension farm advisor attending the June 26 event to better serve growers in Glenn, Tehama and Colusa counties. “The packages look the same. People grab the wrong jug.” And then, disaster.
Instructors were Brad Hanson, professor of Cooperative Extension; and Kassim Al-Khatib, the Melvin D. Androus endowed professor for weed science; both in the Department of Plant Sciences. They were joined by John Roncoroni, a Cooperative Extension emeritus farm advisor rooted in the department's weed science program. Attendees were a mixture of people from agriculture, industry, government officials, university researchers and Cooperative Extension advisors. The event was hosted by the Weed Research and Information Center, based in the Department of Plant Sciences.
Out in a field west of campus, visitors could see the progression of damage, from control plots with green and healthy crops to plants that looked sadder as herbicide concentrations increased. Visitors could see the patterns of damage for common foliar chemicals such as glyphosate, paraquat, and 2,4-D, as well as soil-applied herbicides from several chemical classes.
“There's a lot of detective work,” said Stephen Chang, a master's student in Hanson's lab aiming for a career in Cooperative Extension. “For example, the company that makes the herbicide says there shouldn't be a problem, but the grower says, there is a problem. This course helps with developing the skills to figure out what happened.”
It might not be the herbicide at all
Detective work and problem-solving frame the approach, Hanson explained. The cause of crop damage can be simple or complex. Like a good mystery, what appears to be a clue can turn out to be a red herring. Professionals need to draw on their inner Sherlock Holmes to observe and document symptoms, look for patterns in the plants and in the field, ask questions, gather information about the larger environment and collect samples.
An herbicidal Agatha Christie would then suggest: What if it's not herbicide damage at all? Participants learned to consider the possibility of insects, pathogens and viruses, as well as problems with water, nutrients, soil condition and even root damage from cultivation practices.
Hanson recalled puzzling over symptoms he found in an orchard. The culprit? “A leaking natural gas line,” he said.
More resources for herbicide issues
Participants also heard from Molly Mathews, deputy agriculture commissioner from Yolo County, on how a field investigation is conducted. Lawyer Robert Davies, of Donahue Davies LLP in Folsom, outlined the basics of what happens when there are lawsuits related to crop damage from herbicide drift.
The Diagnosing Herbicide Symptoms field day is part of a larger program of education and outreach offered through the Weed RIC, said director Julia Stover-Blackburn. It was the first time the event has been offered since the COVID-19 pandemic, she added.
- For more information about field days and resources, visit the Weed RIC webpage.
- For a thorough discussion of herbicide symptoms, visit this page overseen by Al-Khatib and sponsored by University of California Agriculture and Natural Resources.
- This online course follows an earlier version of the Diagnosing Herbicide Symptoms field program.
This story was originally published on the UC Davis Department of Plant Sciences website.
UC food-safety specialist tests biosensors to ensure safe produce
Ahmed El-Moghazy joined UC Agriculture and Natural Resources as a UC Cooperative Extension food safety specialist in February and is based at UC Riverside. Food safety, according to El-Moghazy, are measures that ensure food is free from harmful contaminants, prevent foodborne illnesses and is safe to eat. El-Moghazy is responsible for assisting California farmers and food processing facilities to enhance food safety practices by training appropriate personnel and addressing food-safety issues on their farms.
As the principal investigator for the 2-SAFE Lab at UC Riverside, El-Moghazy is investigating the accuracy and applicability of point-of-use biosensor technology. The small, lightweight and easy-to-use sensor can be used while out in the field or in a packing house to test contamination of liquids such as irrigation and washing water or solids like food samples.
Testing for foodborne pathogens traditionally takes two to three days and the process can be costly. The biosensor technology that El-Moghazy is using is inexpensive and can provide results within one work shift, which allows businesses that grow fresh produce to confirm the safety of their products before sending them to the market.
The alternative, selling contaminated food to consumers, is not only detrimental to human health, but can ruin the reputation of businesses, making way for unanticipated costs associated with recalling contaminated products and regulatory consequences including fines and sanctions.
El-Moghazy is also developing the next generation of antimicrobial surface coatings and materials that can rapidly control the foodborne pathogens and hinder the transfer of harmful bacteria from contaminated food to non-contaminated food.
El-Moghazy is optimistic that his research can safeguard public health, reduce the burden of foodborne illness and protect the integrity of businesses. Although El-Moghazy serves the entire state, he is dedicating a large part of his needs assessment and efforts in Southern California where high-value specialty crops such as avocados and citrus are grown.
"Did you know that one in every six Americans get sick from eating food contaminated with a foodborne pathogen?" asked El-Moghazy. Understanding the fatality of foodborne illnesses, El-Moghazy believes that increasing awareness through education is an essential aspect of his role. "It's true, but not many people realize this, or that 40% of foodborne illnesses stem from fresh produce."
To protect consumers, the U.S. Food and Drug Administration requires farms with a certain level of annual sales (adjusted for inflation) of fruits and vegetables typically consumed raw to have one employee who has completed an FDA-approved Produce Safety Rule Grower Training.
In addition to certified trainings, El-Moghazy offers technical assistance to ensure growers comply before and after inspections, as well as resources for several topics including produce safety, agriculture water, flooding, soil amendments, worker health, hygiene and training and postharvest handling and sanitation. He can also assist in developing food-safety plans and other general farm food-safety protocols. His technical expertise covers all aspects of food production and supply including irrigation water quality, hygiene of harvesting tools and transportation.
Before joining ANR, El-Moghazy completed two years as a visiting scholar in the UC Davis Biological and Agricultural Engineering department before continuing as a postdoctoral fellow in the UC Davis Food Science and Technology department for 5 years. Much of his work was rooted in the development of biosensors and antimicrobial materials for food safety. While in Davis, he collaborated with local farms and food processing companies on food safety research and extension.
El-Moghazy earned a Ph.D. studying developmental biosensors for food safety applications to detect pesticides residues from a joint program offered by University of Perpignan in France and Alexandria University in Egypt. He also earned a master's degree in developmental biobased fungicides and a bachelor's in agriculture science from Alexandria University. Finally, he completed a fellowship at the Institute of Plant Protection, Szent Istvan University in Hungary, where he studied how to extend shelf-life of fresh produce using biomaterials.
El-Moghazy is based at UC Riverside in the Department of Microbiology and Plant Pathology. He can be reached at aelmogha@ucr.edu or (951) 827-0257.
Report outlines top concerns in California organic agriculture
Organic Agriculture Institute needs assessment refines how it can address pressing challenges
The explosive growth of organic agriculture in the U.S. – reflected in a 90% increase in organic farms from 2011 to 2021, according to U.S. Department of Agriculture statistics – has come at a cost for some farmers. With new farming operations increasing the supply of organic commodities, along with consolidation of buyers, growers report that their profit margins are not what they used to be.
Those market size considerations are among the challenges highlighted in a new report detailing the initial findings by the University of California Organic Agriculture Institute on the most pressing needs of the state's organic sector. OAI gathered and analyzed data from 423 responses to an online grower survey, over 60 interviews with stakeholders across the organic community, and additional observations from farm visits and workshops.
The report describes other frequently mentioned systemic priorities, such as maintaining integrity of the term “organic,” developing a market for organic seeds, spreading consumer awareness, and alleviating the burdens of organic certification and reporting.
Shriya Rangarajan, the postdoctoral researcher with OAI leading this statewide needs assessment, said that the reported challenges varied by organic status (fully certified, transitioning to organic, or a mixed farm with some conventional), type of crop, as well as size of the operation. She noted survey respondents were roughly representative of the sector overall – 70% small-scale growers and 30% medium and large.
“Organic is not a homogenous industry, to say the least – small growers and large growers are very different; for small growers, their challenges tend to be financial and regulatory, especially relating to certification requirements and labor,” said Rangarajan. She added that larger growers mentioned different types of challenges, weeds and pest pressures for instance, given the difficulty in controlling managing these at scale without the use or availability of organic inputs.
Organic Agriculture Institute key to sharing resources across state
Another common theme from the assessment is that the organic sector needs more accessible resources to address those myriad concerns. For OAI, established in 2020 under UC Agriculture and Natural Resources, the initial findings validated and refined the direction of its research and extension programs.
“As a new organization, we've been trying to figure out where we fit into this ecosystem and how we can support it,” said Houston Wilson, a UC Cooperative Extension entomology specialist who has served as OAI's director since its founding.
Because OAI was envisioned as a hub of resources and connections for California's organic community, Wilson and his colleagues are especially interested in understanding how its constituent members obtain information – and how OAI can improve their access.
“Growers are finding it difficult to navigate the resources that exist for organic agriculture, like technical information, financial support, compliance and certification support,” Wilson said. "While we'd like to see more resources for organic in general, those that currently exist can sometimes be hard to navigate or it can be hard to know where to go for the right thing – that became really apparent early on.”
While some producers are contacting OAI directly with their questions, Wilson is eager to develop tools and systems that can serve the community more broadly. For example, Wilson and Krista Marshall – OAI's policy and partnerships coordinator – are currently beta-testing a new map tool, built in conjunction with UC ANR's Informatics and GIS (IGIS) team. The map, expected to be ready in fall 2024, will enable users to click on their county and see all available resources related to organic agriculture.
Wilson added that OAI will have four full-time staffers by fall, further expanding its research, extension, and education efforts. After holding four field events this past year, OAI aims to increase activities in the coming year, including not just field events but also online resources, webinars and more. Also, a new training and technical assistance coordinator will be tasked with bringing Cooperative Extension advisors and other technical assistance personnel across the state up to speed on a range of organic topics, so they can more effectively answer questions from clientele in their region.
New survey aims to trace crucial organic knowledge networks
Although the OAI team has gained a sense of how information is shared across the organic community (and started to formalize those interconnections through a California Organic Agriculture Knowledge Network), they are now developing a survey to study those relationships more systematically.
“We're trying to understand what kind of knowledge resources people tap into, which is something that has come up repeatedly in our needs assessment,” Rangarajan said. “We're trying to understand who people are speaking to because, at the end of the day, organic is still a relatively small part of agriculture in California, and that makes it more fragmented. So trying to connect those different parts becomes important.”
Once Wilson has a more nuanced understanding of organic knowledge networks, he will be able to strategize and position OAI – and the UC – as a more effective partner and contributor in the sector.
“Given the history of organic, growers have had to rely on each other a lot,” Wilson explained. “We understand that the university has unique expertise to bring to the table, but we also acknowledge that there's all these other knowledge holders out there, so one of the roles that we see ourselves having is helping to facilitate those connections, strengthen them and increase the frequency of interaction.”
That may include further supporting efforts that connect transitioning organic farmers with experienced growers (a mentorship program led by Certified California Organic Farmers, or CCOF), or giving more structure to grower-researcher partnerships that can help address a host of production challenges. In OAI's grower survey, weed management topped the list, followed by water and disease issues, all exacerbated by climate variability.
“I think a lot of the real innovation changes are coming through growers experimenting with their own practice,” Rangarajan explained. “From a research perspective, one of the best ways to take this forward would be to formalize those experiments in some way so that knowledge becomes more reportable.”
And collaboration on “organic topics,” such as finding alternatives to synthetic pesticides, are a boon to the entire agricultural sector – conventional growers included.
“Everyone is trying to reduce pesticide use; everyone is trying to reduce environmental impacts,” Wilson said. “You don't have to be certified organic to benefit from organic research; these practices can be used by anyone.”
The report with OAI's initial findings on organic needs can be found at: https://ucanr.edu/sites/organic/files/396228.pdf.
Postharvest Center: New research focus and outreach
Still providing the world with top-notch information
UC Davis has been a leading source of information for people handling, packaging and transporting crops since the beginnings of the Postharvest Research and Extension Center in 1979. Now, the center is strengthening its focus on the needs of industry, offering fresh courses, weaving strategic partnerships and expanding into digital media, all while building up its research capacity to better serve the needs of the produce industry.
“We're asking people in the industry, ‘How can we support you? How can we better listen to you?' We want people to know we're not disconnected know-it-alls,” said new center co-director Bárbara Blanco-Ulate, an associate professor in the UC Davis Department of Plant Sciences. “We're getting more faculty involvement, people with expertise in related fields such as quality engineering and safety, as well as bringing in emeriti faculty and people from around California. We're forming partnerships with organizations around the world, and we've opened up to people from other institutions around the country.”
“The larger the network, the more things we can do,” added fellow co-director Irwin R. Donis-Gonzalez, an associate professor of UC Cooperative Extension in the Department of Biological and Agricultural Engineering.
The foundation: Expanded research
The new co-directors will beef up the center's applied science component with the hiring of a research specialist. They aim to provide new information that can be used industry-wide as companies explore new ways to handle and store fresh produce.
“We're building the capacity to respond to industry requests for research,” Blanco-Ulate said.
New courses, national reach
Their first workshop, held recently, demonstrates the center's renewed vision and commitment to broad networking: The Agricultural Water Systems Workshop addressed current concerns around water management and risks to food safety. Partners in the course included the Western Growers Association, the University of Arizona, the University of Florida and Salinas-based Taylor Fresh Foods, Inc.
Courses given over the past several years that have been recorded will be posted to the center's new, online video library and to the center's YouTube channel.
“People can watch those courses for free,” Blanco-Ulate said. In addition, new courses will be offered in-person and hybrid.
The co-directors are working with the University of California to offer continuing and professional education credits to course participants.
Online resources – many for free!
The center's website features a database with scores of free product fact sheets, which are downloaded by users around the world. The fact sheets are so highly regarded that they are considered expert evidence in legal proceedings, Blanco-Ulate said. Visitors to the website can also find links to research papers published by UC Davis faculty, including seminal works by Adel Kader, who founded the center.
Books are offered through the center's online bookstore and include titles through UC Agriculture and Natural Resources. Ten new titles are being planned, including topic-specific updates taken from previous classics.
Debunking myths: Ethylene
A new newsletter deals with a new problem: Misinformation about food and food handling that spreads through social media. One example is the use of ethylene to ripen produce such as bananas, so that they can be safely stored until ready for the consumer.
“Ethylene is safe for humans and does not leave any harmful residue on produce,” Donis-Gonzalez wrote in the center's latest newsletter. Even better news, he added: The levels of ethylene used on food are a tiny fraction of the concentrations that would be needed to create an explosion, one of the false alarms being raised in social media.
Evolving with the times
After 47 years of service, these and more updates will keep the center at the forefront of an evolving postharvest world. The top goal: Meet the needs of agriculturalists, industry and consumers.
“We are adapting to new needs, with both the resources and the workshop we're offering,” Donis-Gonzalez said.
“As a land-grant institution, we take our outreach mission seriously,” Blanco-Ulate added.
Related links
More about the UC Davis Postharvest Research and Extension Center.
This story first appeared on the UC Davis Department of Plant Sciences site.
