Posts Tagged: Strawberries
Strawberries, which generated $2.2 billion for California growers mainly on the coast in 2019, are sensitive to soilborne diseases. Strawberry plant roots infected by fungi are unable to take in nutrients and water, causing the leaves and stems to wilt. The diseases reduce fruit yields and eventually kill infected plants.
To protect the delicate plants from pathogens, strawberry growers fumigate the soil with pesticides such as chloropicrin and 1,3-dichloropropene before planting transplants. Due to the potential negative effects on the environment and human health, however, use of fumigants are highly regulated and developing non-fumigant alternatives has been a priority of the strawberry industry.
For a biological alternative to manage soilborne diseases in strawberries, Joji Muramoto, UC Cooperative Extension organic production specialist based at UC Santa Cruz, has received a $411,395 grant from USDA National Institute of Food and Agriculture to study the ability of other crops to suppress strawberry pathogens in the soil.
Verticillium wilt, caused by Verticillium dahliae, is a common soilborne disease that can be controlled with anaerobic soil disinfestation (ASD), a fermentation-based biological treatment using carbon sources such as rice bran under plastic mulch in moist soils for 3 to 5 weeks in autumn. About 2,000 acres of berry fields, mostly organic, were treated with ASD in California and Baja California, Mexico, in 2019.
In 2008-09, the diseases fusarium wilt, caused by Fusarium oxysporum f. sp. fragariae, and charcoal rot, caused by Macrophomina phaseolina, emerged in Southern California and now threaten strawberry plants throughout the state.
ASD isn't as effective against F. oxysporum and M. phaseolina unless it is applied in summer on the coast. As saprophytes, they feed not only on living plants, but also can colonize crop residues and rice bran especially at lower coastal temperatures in autumn. Treating fields on California's coast with ASD during summer is difficult because it competes with the vegetable production period.
Based on promising studies in Asia and other areas, Muramoto plans to test alliums – such as onion, bunch onion and leek – and a certain variety of wheat (Summit 515) to see if they will suppress F. oxysporum and M. phaseolina. His team will conduct a series of greenhouse and field trials and test these crops with and without ASD to compare the effects on soilborne pathogens.
“Studies have shown the potential of using allium crops to control Fusarium wilt, and Summit 515 wheat for charcoal rot,” Muramoto said. “Our goal is to examine the effectiveness of suppressive crops, optimize them for California strawberry production systems, and evaluate their economic feasibility for commercial use.”
“No single tactic is likely to replace fumigants,” he said. “Integration of multiple biological approaches such as crop rotation, ASD, and use of resistant strawberry varieties is a key to develop a successful non-fumigant-based soilborne disease management strategy for strawberries. This project is a part of such broader efforts.”
At the end of the three-year study, he plans to share the results at workshops, field days and webinars.
Rachael Goodhue, UC Davis professor of agricultural economics; Carol Shennan, UC Santa Cruz professor of environmental studies; and Peter Henry, USDA Agricultural Research Service plant pathologist, are co-principal investigators on the study with Muramoto.
Also collaborating on the project are Christopher Greer, UC Cooperative Extension integrated pest management area advisor in San Luis Obispo County; Oleg Daugovish, UCCE vegetable and strawberry advisor in Ventura County; Mark Bolda, UCCE director strawberry and cane berry advisor in Santa Cruz County; Jan Perez, food systems specialist, and Darryl Wong, farm research manager, at UC Santa Cruz Center for Agroecology and Sustainable Food Systems; Miguel Ramos of Ramos Farm; Agriculture and Land-Based Association (ALBA); Driscoll's; Naturipe; and The Oppenheimer Group.
Central Valley residents from Visalia to Sacramento look forward every year to the beginning of strawberry season in early April, when roadside strawberry stands operated by Hmong and Mien farmers open to the public.
These farms grow strawberry varieties such as Chandler and Camarosa that haven't traded flavor for shelf life – they don't ship or store well, but they are far sweeter than varieties usually sold in stores, and they reach their peak ripeness and flavor in the fields next to the strawberry stands.
As strawberry season opens this year, farmers are hoping that customers will still stop by the stands to pick up their fresh, seasonal strawberries, and also that they will observe 6-foot social distancing and other guidelines to reduce the spread of COVID-19. UC Cooperative Extension agricultural assistant Michael Yang and I were interviewed on a local news station to encourage Fresno residents to practice these guidelines while supporting local farmers.
To assist Fresno strawberry farmers, the UCCE small farms team in Fresno County developed, printed, and distributed signs for roadside strawberry stands reminding customers to observe social distancing and other safety practices, as well as guidelines for farm stands to reduce the spread of COVID-19. Versions of the signs were also developed for strawberry stands in Merced and Sacramento, as well as a general sign for local produce at any farm stand.
Signs and safety guidelines were printed with funding from the Western Extension Risk Management Education Center, and Michael Yang distributed large printed versions of the signs to all strawberry stands on the Fresno County Fruit Trail map in Fresno County. These materials have also been shared with UCCE small farms and food systems advisors as well as nonprofit and agency partners and county Agricultural Commissioner's offices, and they are available for printing on the UCCE Fresno strawberry website.
Road side stands selling fresh strawberries and vegetables are opening up around the San Joaquin Valley, and are a excellent option for safe shopping, reported Dale Yurong on ABC 30 News in Fresno.
In keeping with social distancing guidelines, Yurong conducted remote interviews with UC Cooperative Extension advisor Ruth Dahlquist-Willard and agricultural assistant Michael Yang, who work closely with small-scale farmers in Fresno and Tulare counties.
Dahlquist-Willard suggested customers maintain a six-foot space from other shoppers at farm stands and follow other common sense precautions when purchasing the healthful fresh food by, "not touching any produce that you're not planning to buy, leaving as soon as you've made a purchase and washing the produce when you get home . . . . Similar to what we're seeing at farmers markets right now."
Some valley farmers have been selling their produce at farmers markets out of town and have noticed fewer people are out shopping, Yurong said. They hope more people will stop by the local farm stands, away from the crowded grocery stores, and pick up something straight out of the field.
"My farmers that go to farmers markets, even though the farmers market is still open, they only allow a few people at a time. You don't have a lot of customers walk by just like before," Yang said.
San Joaquin Valley strawberry stands were all expected to be open by April 10, Yurong said.
COVID-19 does not currently pose major threats to overall global food security because adequate stores of staples — like wheat and rice — remain available. But the sustainability of California specialty crops may face greater hurdles, reported Laura Poppick in Scientific American.
Poppick spoke with two UC Agriculture and Natural Resources (UC ANR) scientists for perspective on the future of California agriculture considering the market and production constraints posed by measures to slow the spread of the coronavirus.
“Everybody is scrambling to figure out what to do,” said Gail Feenstra, deputy director of UC ANR's Sustainable Agriculture Research and Education Program. “There's just a lot of disruption.”
Specialty products — such as some fruits and organic produce grown on smaller-scale farms — are often sold to restaurants and farmers markets, many of which are now closed or have reduced service, rather than directly to the grocery stores that are still operating. Even if these farmers are able to continue working, they may have limited places to sell their goods, the article said.
Strawberries are another crop likely to be affected. Laborers picking strawberries typically work more closely than is advisable to prevent the spread of the virus, said Mark Bolda, a University of California Cooperative Extension farm advisor based in Watsonville. He said farmers are already making plans to spread workers between rows.
Strawberries, however, hit prime ripeness within a narrow window of just two to three days and must be picked quickly, Bolda says. Spacing workers may slow picking, and, "being slower is expensive."
Farmers who are considering growing romaine hearts or organic strawberries in California's Central Coast region can get some help determining whether the crop will pencil out for them.
UC ANR Agricultural Issues Center and UC Cooperative Extension have released sample costs to produce and harvest organic strawberries for fresh market and romaine lettuce hearts in Santa Cruz and Monterey counties.
A major difference between growing strawberries organically and the conventional practice is in weed control.
“Weed management is especially challenging for organic strawberry production because soil fumigation and most herbicides are not allowed under organic regulations,” said Mark Bolda, UC Cooperative Extension farm advisor in Santa Cruz County. “Weeds in furrows between the beds can be mechanically cultivated during the growing season, but most of the weeding will need to be done by hand from December through September.”
The cost analyses are based on hypothetical well-managed farming operations using practices common to the Central Coast region. The costs, materials and practices shown in the studies will not apply to all farms and are intended to assist growers in estimating their own costs.
The organic strawberry study assumes a farm with conventionally grown strawberry transplants planted on 27 contiguous acres of rented land. “Organic strawberry transplants are part of the picture now, but not standard by a long shot,” said Bolda, who co-authored the cost studies. The strawberry crop is harvested by hand and packed into trays containing eight 1-pound clamshells, from April through early October with peak harvest in June and July.
For romaine lettuce for the hearts market, the cost study assumes a farm of 1,500 non-contiguous acres of rented land, with romaine planted on 250 acres and rotated with other lettuce and cool season vegetable crops to assist with pest management and soil fertility. Lettuce is planted continuously from late December to mid-August along the Central Coast. To manage lettuce mosaic virus, Monterey County has a host-free period (December 7 – 21), during which time lettuce may not be planted. In this study, lettuce is planted in January.
For both the organic strawberries and romaine, ranging analysis tables show net profits over a range of prices and yields. Other tables show the monthly cash costs, the costs and returns per acre, hourly equipment costs, and the whole farm annual equipment, investment and business overhead costs. The authors describe the assumptions they used to identify current costs for production material inputs and overhead.
The authors have also expanded the section on labor, which includes information on California's minimum wage and overtime laws.
Growers, UC ANR Cooperative Extension farm advisors and other agricultural associates provided input and reviewed the methods and findings of both studies.
Free copies of these and other sample cost of production studies for many commodities are available. To download the cost studies, visit the UC Davis Department of Agricultural and Resource Economics website at https://coststudies.ucdavis.edu.
For more information about calculations used in the romaine hearts and organic strawberriesstudies, contact the Agricultural Issues Center at (530) 752-4651 or Mark Bolda at UC Cooperative Extension in Santa Cruz County at (831) 763-8025.
The cost and returns studies program is funded by the UC Agricultural Issues Center and UC Cooperative Extension, which are part of the UC Division of Agriculture and Natural Resources, and the UC Davis Department of Agricultural and Resource Economics.