So how much potassium does an almond or pistachio orchard need? How and when should it be applied? Watch this brief interview with UCCE Orchard Systems Advisor Phoebe Gordon as she shares some facts and considerations for growers to maintain a healthy orchard and prevent potassium deficiencies. Read more about best practices for orchard management in Pacific Nut Producer Magazine.
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UC Cooperative Extension specialist Jeff Dahlberg, also the director of the UC Kearney Agricultural Research and Extension Center (KARE) in Parlier, invoked his 35 years of sorghum expertise to increasing interest in growing the crop in California and to better understanding plants’ ability to tolerate drought. Dahlberg retires Jan. 8.
As a Peace Corps volunteer in Niger in the early 1980s, Dahlberg was intrigued by sorghum, a staple food being cultivated by the country’s vast population of subsistence farmers.
“I was impressed with the fact that sorghum was so drought tolerant,” Dahlberg said. “Nigerien farmers relied solely on rain for their sorghum and millet crops.”
Upon returning to the U.S., he earned a master’s degree at the University of Arizona and a Ph.D. at Texas A&M, where his research focused on sorghum. He worked with the USDA Agricultural Research Service in Puerto Rico for 7 years and then spent the next 10 years as research director with the National Sorghum Producers in Lubbock, Texas.
When Dahlberg took the helm of the 330-acre UC agricultural research center in 2010, he and colleagues at the UC West Side Research and Extension Center and at UC Davis began conducting sorghum forage variety trials. Sorghum wasn’t new to California. In the past, it had mainly been used for animal feed. But Dahlberg believed the crop’s adaptability – excellent for forage, biofuels and gluten-free human food – offered the grain a rosy future in the Golden State.
“With our research, we have provided California farmers who are thinking about growing sorghum access to locally generated, research-based information to help them make the decision,” Dahlberg said.
In 2015, Dahlberg and UC Berkeley specialist Peggy Lemaux launched a sweeping drought research project at KARE. The five-year study, funded with a $12.3 million grant from the Department of Energy, researched the genetics of drought tolerance in sorghum and how soil microbial communities interacted with sorghum roots to battle drought stress.
A journal article published in Proceedings of the National Academy of Sciences in 2018 presented the first detailed look at the role of drought in restructuring the root microbiome. The plant switches some genes on and some genes off when it detects water scarcity and access to water.
“That has implications for feeding the world, particularly considering the changing climate and weather patterns,” Dahlberg said.
In recent years, Dahlberg helped reestablish tea research at Kearney, initiated nearly 60 years ago in a study funded by Thomas J. Lipton, Inc. At the time, Lipton was seeking to grow tea for the instant tea market. When the Kearney tea research program was scrapped in 1981, a researcher had a handful of the best tea clones planted in the landscape around buildings at Kearney.
Those shrubs became the basis for a new tea research trial planted at Kearney in 2017 with UC Davis professor Jackie Gervay Hague to determine whether drought stress impacts the production of phenolics and tannins in the tea.
“We know we can grow good tea here and we can grow high tonnage,” Dahlberg said. “We want to determine if we can do that on a consistent basis and whether we can improve tea quality through irrigation management.”
In retirement, Dahlberg plans to relocate to Lake Ann, Mich., to be close to family. UC Cooperative Extension irrigation specialist Khaled Bali will serve as interim director of the UC Kearney Agricultural Research and Extension Center. — By Jeannette Warnert, UCANR
A new study by University of California, Davis, researchers finds a low risk of contamination of foodborne pathogens on produce and meat at Northern California certified farmers markets, but still finds cause for some concern.
The study, published in the Journal of Food Protection, examined the prevalence of Salmonella on meat and produce, as well as the prevalence of generic E. coli on produce. Samples were taken from 44 certified Northern California farmers markets, including in the Sacramento region and Bay Area. Less than 2 percent (1.8 percent) of animal products sampled, including beef, pork and poultry, tested positive for Salmonella, while all produce samples tested negative. Slightly more than 30 percent (31.3 percent) of produce tested positive for generic E. coli. Generic E. coli is an indication of fecal contamination, but not all E. coli is harmful. This study didn’t test for pathogenic E. coli.
“Based on this data, I think it’s safe to consume meat and produce from farmers markets,” said lead author Alda Pires, a UC Cooperative Extension specialist and research scientist in the UC Davis School of Veterinary Medicine. “That’s a low risk of contamination of foodborne pathogens, especially Salmonella.”
While the prevalence of generic E. coli may seem relatively high, the concentrations were low. Pires said that’s especially so compared to previous studies of contamination at farmers markets elsewhere in the United States. The prevalence of Salmonella in meat sampled from Northern California farmers markets is also much lower than what previous studies have found in grocery stores.
Among the produce sampled, leafy greens had the highest prevalence of E. coli, followed by root vegetables.
Consumers should still be cautious
Consumers and farmers should still be aware that produce and meat were not free from contamination. Consumers need to make sure the foods they prepare from farmers markets follow the good hygiene practices recommended by Centers for Disease Control and Prevention. Consumers should also keep produce separate from meat to avoid cross-contamination.
“The study raises awareness that it’s not just very large farms that can have contamination,” said co-author Michele Jay-Russell, with the Western Center for Food Safety at UC Davis. “Farmers need to pay attention to everything they’re doing, from planting to storage, to avoid contamination.”
While certified farmers markets are inspected for food hygiene, microbiological quality is not explored. Smaller farms, those making less than $25,000 a year, are also exempt from certain food-safety provisions of the U.S. Food and Drug Administration’s Food Safety and Modernization Act. Foodborne illness costs the U.S. economy more than $15 billion annually.
Other co-authors include James Stover, Esther Kukielka, Viktoria Haghani, Peiman Aminabadi and Thais De Melo Ramos of UC Davis. Research support came from the U.S. Department of Agriculture. — By Amy Quinton, UC Davis
At Malcolm Media’s recent Grape, Nut & Tree Fruit Expo, UCCE Viticulture Advisor Gabriel Torres provided an in-depth presentation on sour rot prevention and management. If you missed his presentation or would like a refresher, watch this brief interview as Gabriel provides of some key points growers should consider in season-long prevention/management of this crop spoiling complex.
Please thank this video’s sponsor Suterra for their industry support.
Despite the tremendous need, there are currently no preemergence herbicides that are organic-compliant. Steam injected into the soil such that the soil temperatures reach >140°F for 15-20 minutes will kill weed seed in the soil. The effect of this reduction in the seedbank viability results weed control in the treated area that persists for several weeks or months, similar to the effects of a preemergence herbicide.
Two studies were conducted at the USDA Hartnell Farm at Salinas, CA during July to September 2020. Steam was applied to raised beds using a custom-built steam injector. Prior to seeding lettuce, steam was applied in a 4-inch wide band to a depth of 3 inches deep. The steam was supplied by a SF-20 Sioux steam generator at approximately 6 to 9 PSI. Soil temperatures in the treated zone were monitored overnight with Hobo temperature monitors. Treatments tested were steam, steam plus 1% w/w peroxide, and nontreated. Treatments were replicated 4 times and arranged in a randomized complete block design. Peroxide was included as it releases heat when injected into soil, i.e., an exothermic reaction, based on the premise that it supplements the heat released by steam. Data collected were soil temperatures following steaming, weed control, hand weeding times, diseased plant counts, and lettuce yields. Trial 1 was initiated July 1 and harvested August 31, 2020. Trial 2 was initiated July 21 and harvested September 25, 2020. Soil temperature intervals >140°F in the top 4 inches of soil for steam were 88 and 67 minutes for trials 1 and 2, respectively. Similarly, soil temperatures >140°F in the steam + peroxide treatment were 76 and 80 minutes for trials 1 and 2, respectively. In trial 1 steam and steam + peroxide resulted in 90% and 92% weed control relative to the nontreated. In trial 2 steam and steam + peroxide resulted in 66% and 84% weed control, respectively. Steam alone reduced hand weeding times 22% to 35% compared to the nontreated, and steam + peroxide reduced hand weeding times 36% to 40% compared to the nontreated. There were no differences in numbers of plants with lettuce drop (Sclerotinia minor) in trial 1. Compared to the nontreated, lettuce drop incidence in trial 2 was 66% and 59% lower in steam and steam + peroxide treatments, respectively. Lettuce plant diameters in trial 1 found that lettuce grown on steamed soil was 16% larger, but there were no differences in trial 2. Lettuce plants grown on steam + peroxide treated soil were 12% and 23% larger in trials 1 and 2, respectively. There were no treatment effects on yields in either trial 1 or 2.
We are not aware of any commercial scale applicators for lettuce that apply steam in a band to the lettuce bed. However, we are working with Dr. Mark Siemens, an agricultural engineer with the University of Arizona to design a commercial scale applicator. Mark has a prototype applicator built and will be demonstrating it during the winter season in the Yuma Valley. It appears that the design for a steam applicator is not complicated and is well within the capabilities of machine shops in California to build. — By Nelly Guerra & Steven Fennimore, UC Cooperative Extension
A new study on the costs and returns of establishing and producing lemons in Ventura County has been released by UC Cooperative Extension in Southern California and UC Agricultural Issues Center, both part of UC Agriculture and Natural Resources.
“Coastal agriculture is always in transition and as strawberries and vegetables become less profitable due to markets and labor availability, lemons have returned as a potentially profitable alternative to those crops,” saidBen Faber, UC Cooperative Extension farm advisor for Ventura County and coauthor of the study.
California lemon acreage was at roughly 47,000 acres in 2018-19, of which Ventura County accounts for 31%, according to the 2019 Ventura County Crop Report. Ventura County was growing lemons on 14,407 acres in 2019.
“The profitability of lemon production depends on the price of land,” said Etaferahu Takele, UC Cooperative Extension farm management advisor for Southern California, another coauthor of the study. “If the price of land continues in its current trend, it could be prohibitive for new entrants to make a profit and limit further expansion of lemon production in the county.”
Their cost analysis describes production operations for Eureka lemons on macrophylla rootstock, which are planted at 155 trees per acre with an expected life span of 40 years.
The study includes a detailed summary of costs and returns and a profitability analysis of gross margin, economic profit and a break-even ranging analysis table, which shows profits over a range of prices and yields.
Input and reviews were provided by Ventura County farm advisor and grower cooperators. The authors describe the assumptions used to identify current costs for lemon establishment and production, material inputs, cash and non-cash overhead.
The new study, “2020 – Sample Costs to Establish and Produce Eureka Lemons in Ventura County,” can be downloaded for free from the UC Davis Department of Agricultural and Resource Economics website at http://coststudies.ucdavis.edu and the UCCE Riverside County Farm Management website at https://ucanr.edu/sites/Farm_Management/files/338947.pdf. Sample cost of production studies for many other commodities are also available on the websites.
For additional information or an explanation of the calculations used in the studies, refer to the section of the report titled “Assumptions” or contact Takele at (951) 683-6491 Ext. 243 ettakele@ucanr.edu or Donald Stewart at the UC Agricultural Issues Center at (530) 752-4651, destewart@ucdavis.edu.
For information about production of lemons in Ventura County, contact Faber at bafaber@ucanr.edu. — By Pamela Kan-Rice, UCANR
Steve Fennimore, UC Davis Plant Sciences faculty member and UC Cooperative Extension weed specialist, and colleagues received the 2020 EurAgEng Outstanding Paper Award for the paper, “Crop Signalling: A Novel Crop Recognition Technique for Robotic Control,” which was published in Biosystems Engineering.
The research represents a breakthrough in differentiating weeds from crops using machine vision systems. The technology could help California growers address challenges in managing weeds in in dozens of crops with limited herbicide options, and significant hand-weeding costs due to a growing labor shortage.
“California growers would benefit from improved weeding technology,” said Fennimore. “This technology certainly has commercialization potential by improving the accuracy, speed and reliability of weed/crop differentiation by weeding machines.”
Field experiments were successfully conducted for real-time weed control in tomato and lettuce. The paper was a collaborative effort led by first author Rekha Raja, a postdoctoral scholar in the UC Davis Department of Biological and Agricultural Engineering, and included researchers from the UC Davis Departments of Plant Sciences and Plant Biology; UC Cooperative Extensions in Santa Cruz and Monterey Counties; and the Department of Biosystems Engineering at the University of Arizona.
Awarded by the European Society of Agricultural Engineers, the EurAgEng Outstanding Paper Award is only awarded once every two years and is selected out of all the papers published in Biosystems Engineering. – By Kristin Burns, UCANR