Posts Tagged: strawberries
The strawberry industry ended a long good-bye to methyl bromide in 2016. The fumigant had been used for decades to kill a wide range of soil-borne pathogens, weed seeds and insects, permitting the California strawberry industry to flourish. Scientists determined it was an ozone-depleting chemical in 1991, but its phase-out was delayed for years because of lack of equally effective alternatives.
Strawberry farmers now use a combination of approaches, including fumigation with other chemicals, soil oxygen deprivation, biofumigants, and beneficial microbes that improve soil biology. A greater arsenal is needed.
“Growers have three or four chemical alternatives, some are used alone and others in various combinations,” said UC Cooperative Extension advisor Surendra Dara. “Now, certain minerals, beneficial microbes and biostimulants are becoming available to enhance plant's natural defenses and improve strawberry growth, yield and health in an era without methyl bromide.”
Dara conducts research and advises strawberry and vegetable growers in the Central Coast counties of San Luis Obispo and Santa Barbara. Each year he holds a field day that attracts nearly 200 farmers, pest control advisers and representatives of allied industries to Manzanita Berry Farms outside Santa Maria. The agenda for the May 9 event included preliminary results of trials studying a number of commercially available and soon-to-be available biological and synthetic amendments to improve strawberry plant health, berry quality and yield.
Dara was ill, so Manzanita Farm owner Dave Peck reviewed the handout prepared by Dara for the field day. Manzanita Farms is one of two sites where Dara is testing products in replicated plots. Other studies are conducted in strawberries grown at the Shafter Research Station, a privately managed agricultural research facility in Kern County.
Several products resulted in increased marketable yield of strawberries during the February 2018 to April 2018 study period. See the preliminary results here. Data collection will continue through the end of the strawberry season.
“A challenge was that many people did not have complete faith in biologicals a few years ago,” Dara said. “By conducting multiple studies year after year, we are able to generate critical data that is useful for the farmers as well as companies that produce biologicals. By using different application strategies and rates, and a combination of techniques - as appropriate for their situations - farmers can engage in sustainable strawberry production.”
Each fall, strawberry farmers put young strawberry transplants in the ground through holes cut in plastic mulch. Beneath the mulch are drip lines that will serve to irrigate the plants as they reach maturity. But early on, farmers typically install solid-set aluminum sprinklers in the furrows to get the plants started and leach salts below the strawberry plants' root zone.
“In some areas, overhead aluminum sprinkler irrigation is considered very important to prevent dry conditions which could result from Santa Ana winds,” Dara said. “However, the aluminum sprinkler irrigation requires a significant amount of water and can be inefficient.”
During the 2014-15 strawberry season, Dara worked with farmer Dave Peck of Manzanita Berry Farms in Santa Maria to compare micro-sprinklers with the more commonly used aluminum sprinkler systems. The experimental plots were planted in early November and carefully monitored throughout the growing and harvest season, which ended in June. The two types of sprinkler irrigation were used for about one month, then the grower switched to using exclusively the drip irrigation installed underneath the mulch.
Dara found that micro-sprinkler irrigation cut water use by 32 percent compared to the area where aluminum sprinklers were used, and resulted in no significant difference in total marketable yield.
Strawberry plant vigor was measured each month during the study. At first, the plants in the micro-sprinkler treatment area were significantly smaller, but they caught up with the rest by March. Sprinkler irrigation is also thought to help control twospotted spider mites and predatory mites. In Dara's experiment, however, the pests' sparse numbers did not allow for useful data to be collected.
The sprinkler comparison did offer insight on powdery mildew, a serious disease problem, particularly for organic strawberry growers. Sampling for powdery mildew in the plots showed that its severity was significantly less in the micro-sprinkler treatment. Another common strawberry production problem, botrytis fruit rot, was also eased with the micro-sprinkler treatment.
RDO Water and Netafim were partial funders of the project.
The full research report is posted on Dara's eNewsletter.
An initiative to improve California water quality, quantity and security is part of the UC Division of Agriculture and Natural Resources Strategic Vision 2025.
Author: Jeannette Warnert
Extending research information is an important part of UC ANR Cooperative Extension. As communication technology is advancing every day, using modern channels of communication are important for successfully reaching out to growers, pest control advisers (PCAs), and other key players of the agriculture industry. Traditional newsletters (Central Coast Agriculture Highlights), blogs (Strawberries and Vegetables and Pest News), Facebook, Twitter (@calstrawberries and @calveggies), Tumblr, and online repositories of meeting handouts and presentations are some of the tools that play a critical role in making important information about the Central Coast strawberry and vegetable extension program readily available to the agricultural industry. The popularity of smartphones has made this information even easier to access.
Smartphone applications are becoming popular in agriculture to provide information and for decisionmaking. However, because there were no such applications to help California strawberry and vegetable growers, IPMinfo was developed. The first version of the app was released in December 2014 and an updated version was released in April 2015.
Growers can find information on invertebrate pests, including as aphids, cyclamen mite, greenhouse whitefly, lygus bug, spider mite, and western flower thrips. Diseases include angular leaf spot, anthracnose, botrytis fruit rot, charcoal rot, common leaf spot, fusarium wilt, leaf blotch and petiole blight, leather rot, mucor fruit rot, phytophthora crown rot, powdery mildew, red stele, rhizopus fruit rot, verticillium wilt, and viral decline. Each pest entry has information on biology, damage symptoms, and management options with associated photos. Links provided in the management section will take the user to the UC IPM website for more detailed information, especially about various control options.
To download the app on iPhones, go to the App Store and search for IPMinfo.
Author: Surendra Dara, UC ANR Cooperative Extension advisor, San Luis Obispo and Ventura counties
Writing on Earth Day, I am reminded of one of the world's major successes in environmental protection, the Montreal Protocol. Originally signed in 1987, it works to phase out ozone-depleting substanc
Twenty-seven years later, the realities of enacting the Montreal Protocol are still taking shape, and strawberry growers are, with each harvest year, a step closer to a complete phase out of the fumigant and increased restrictions on alternative chemical fumigants used for disease suppression.
UC research has focused on how to make an economically viable and effective transition away from the soil fumigant. Initial alternatives include replacement chemical fumigants as well as biological fumigants such as anaerobic soil disinfection (such as putting tarps over fields to decrease oxygen), mustard seed meal amendment, or steam disinfestation.
But what if a practice many growers already use could also serve to suppress soil-borne diseases? What if growers could use a substance that provides multiple on-farm benefits?
Many conventional and organic growers alike use compost to boost soil fertility and organic matter. But compost's potential to serve other purposes, including suppressing disease, remain largely unexplored.
Ph.D. student Margaret Lloyd and Tom Gordon, professor in the Department of Plant Pathology at UC Davis, are hoping to close the gap in that knowledge. With a grant from the National Strawberry Sustainability Initiative, a program administered by University of Arkansas and funded by Walmart Foundation, and funding from UC Sustainable Agriculture Research and Education Program, Lloyd's research seeks to understand whether compost can contribute to disease suppression on a commercial scale, and how growers can best incorporate compost into their farm management to see its benefits.
“Compost is part of the production system that has potential as biological control,” says Lloyd. “Historically, we've only focused on it as a source of organic matter or soil nutrients. I'm trying to characterize its role in root health and soil health.”
The study evaluates the root health of strawberry plants, and compares plant yield and disease suppression across a number of research sites and compost types.
“In general, we talk about compost just as compost,” Lloyd said. “But it has drastically different qualities — soil fertility characteristics, physical properties, and microbial profiles. By focusing on different compost sources, the study will help growers better assess their available compost options to m
Alternatives to methyl bromide have been a long time coming. “The research suggests that it won't be one technology replacing another, but a package of tools to help growers manage disease suppression in the soil,” Lloyd said. If some of those tools are already in a grower's tool kit, the transition away from fumigants will be that much smoother.
The research suggests a powerful Earth Day message for me: use what you have, but seek a deeper understanding of just how to use it.
Lloyd's research findings will be completed in 2014, with results available for growers in 2015. Visit the project's website for more information.