California Fruit and Vegetable

Tag: UF/IFAS

  • Promising Advancements in Biocontrol Treatment that Slows Citrus Greening

    Citrus growers may have a new tool to help them slow the presence of citrus greening in already diseased trees. While there is no cure for Huanglongbing (HLB), researchers at the University of Florida Institute of Food and Agricultural Sciences found that injecting a benign Xylella fastidiosa EB92-1 bacteria biocontrol into infected citrus trees over a period of six years reduced the incidence of trees with severe HLB symptoms. The potential result is providing growers with a strategy to keep trees alive and productive longer even when infected with the citrus greening bacterium.

    Donald Hopkins, an emeritus professor of plant pathology at the UF/IFAS Mid-Florida Research and Education Center, conducted three trials in central and eastern Florida with commercial groves of Valencia orange and Rios grapefruit trees at different maturity stages. All of the trees tested positive for citrus greening disease at the beginning of the trial but had varying ranges of symptoms from asymptomatic, mild to severe. Trees in the trials included young 2-year-old and mature (greater than 20-year-old) trees.

    “Using EB92-1 provided a level of control of HLB in two mature citrus tree trials and in a trial initiated in young 2-year-old trees,” said Hopkins. “This biocontrol strain has the potential to prevent or delay severe symptoms of HLB and prevent the loss of production both in mature and young citrus trees.”

    All trees in the trials remained positive for HLB throughout the six-year trial. The injections of EB92-1 did not prevent or reverse infection of HLB. But key findings indicated that trees that were treated had less increase in symptoms than untreated trees. Injected trees also had increased yield than untreated trees. In mature trees, results from the trials indicated that the most effective control of HLB may require once-a-year treatment for at least the first 2-3 years. Retreatment may be required yearly for best biocontrol.

    Using EB92-1 especially combined with nutrition, fertilizer and pesticide best management practices could prolong the life and productivity of citrus trees.

    Hopkins believes that the biological control of HLB by EB92-1 is not from direct competition with the HLB pathogen since the EB92-1 bacterium operates in a tree’s xylem and the HLB bacterium colonizes the tree’s phloem. Rather the impact in more likely an instance of induced resistance. Induced resistance occurs when a plant’s resistance mechanism is activated by infecting a plant with a pathogen, such as the benign strain EB92-1. In this case, injecting EB92-1 provided some control of HLB in a tree’s tissues not infected with EB92-1 resulting in a slowing of HLB symptoms.

    This research was published online in Plant Disease, the journal of the American Phytopathological Society (APS). The project was partially funded by the United States Department of Agriculture HLB Multi-Agency Coordination (MAC) group and UF/IFAS. This treatment is patented and licensed to an external company but is not currently available to growers. The trials continue in central and eastern Florida. — By Ruth Borger, University of Florida, Institute of Food & Agricultural Sciences

  • An Aromatic Tomato Could be Looming – a La Heirloom Varieties

    You can scarcely find a tasty, heirloom tomato in the grocery store. But University of Florida scientists helped discover a way to enhance tomato smell and taste. Breeding efforts over the last half century have emphasized traits that are important to producers – yield, disease resistance, appearance and post-harvest shelf life among them.

    While those traits are important, modern commercial varieties tend to fall short of the flavor potential shown in older varieties. But consumers want tomatoes that taste and smell good.

    Indeed, in a study published in 2012, consumers who taste-tested several tomato varieties preferred tomatoes with high levels of nitrogenous volatiles.

    For years, consumers have lamented what they deem as the bland taste of tomatoes. Any flavor you savor when you bite into the fruit comes from a combination of many aroma compounds. Some of those compounds contain nitrogen, and they add fruity, floral and tomato vine profiles to the flavor mix. Working on an international team of scientists, two UF/IFAS researchers helped find a route to several important nitrogen-containing tomato flavor compounds.

    In a newly published study, scientists showed that five of the compounds are part of a biochemical pathway for synthesis of these important flavor compounds.

    Using a closely related fruit, Solanum pennellii, scientists found a site on a chromosome essential to produce detectable nitrogenous volatiles in tomatoes, said Denise Tieman, a UF/IFAS research assistant professor of horticultural sciences.

    That data led scientists to identify a step in the pathway to nitrogen-containing flavor compounds.

    “Now that we know how these compounds are made in tomatoes, we can identify varieties that have the heirloom version of the enzyme and high levels of these flavor compounds, and we can breed this trait into modern tomatoes to improve flavor,” Tieman said.

    Tomatoes produce many aroma volatiles, including nitrogen-containing volatiles that are relatively rare in other fruits.

    Since these volatiles are active at low concentrations, increasing their levels does not impact yield or fruit size.

    Tomatoes are the most valuable fruit produced worldwide. Indeed, in 2020, American farmers harvested about 12,600 tons of fresh market tomatoes and 11 million tons of processing tomatoes from 273,00 acres. That adds up to $1 billion in revenue. Florida harvested 26,000 areas of tomatoes during the 2018-2019 season, valued at almost $426 million.

    The new research, published recently in the Proceedings of the National Academy of Sciences, was led by Harry Klee, a UF/IFAS professor emeritus of horticultural sciences and Charles Goulet, a professor of plant science at Universite Laval in Quebec City, Canada. — By Brad Buck, University of Florida Institute of Food & Agricultural Sciences

  • Citrus Growers Join Researchers for Field Day of Emerging Answers

    University of Florida Institute of Food & Agricultural Sciences — More than 50 citrus growers and researchers attended a field day to view 154 new citrus scion-rootstock combinations—some of which will result in the production of market-ready fruit from trees that tolerate the most serious citrus disease worldwide.

    The disease is called citrus greening. It has reduced Florida citrus production to about half of what it was when 950,000 acres were under citrus production. Most researchers and growers agree that new scion and rootstock combinations hold a lot of possibility to preserve Florida’s signature crop.

    The Millennium Block Drive-Thru Field Day 2021 took place on the morning of Thursday, Oct. 14, at the University of Florida Institute of Food and Agricultural Science’s Indian River Research and Education Center (UF/IFAS-IRREC) in Fort Pierce, Florida.

    IRREC researchers guided attendees from information tents positioned at strategic points among 20 acres of carefully managed rows of grapefruit, orange, pummelo, and mandarin trees. Each plot of a scion-rootstock combination was labeled and corresponded to a 12-page packet Ronald Cave and researchers presented to visitors upon arrival. Cave is professor and director of IRREC, and he leads the citrus research project, along with manager Tom James, graduate student Martin Zapien, and agricultural assistant Mac Hossain.

    “Our mission for the Millennium Block’s rootstock and scion trials is primarily to provide guidance to growers on the UFR rootstocks. There is also a secondary purpose to evaluate grapefruit and grapefruit-like hybrids,” said Cave. “No other trial like this is happening anywhere, but we need additional funding to continue with the trial until the trees are seven years of age.”

    University officials and staff guided visitors to specific trees where growers left their vehicles to observe trees up close.

    “The Millennium Block research project is taking the industry’s best scions and rootstocks and mixing and matching them to provide the industry with a brighter future, and some of the matches look promising,” said Doug Bournique, executive vice president of the Indian River Citrus League.

    Jeanna Mastrodicasa, UF/IFAS Associate Vice President for Operations, led the event at booth #2. She fanned through the pages of the packet Cave gave her and noted the colored rows and legends. “Here is a great map and a great key that explains how the coding works and which rootstock appears where in the grove,” said Mastrodicasa.

    In a row of grapefruit trees across from Mastrodicasa, IRREC Advisory Committee member Pete Spyke pointed to six trees of the same rootstocks. Spyke is a heritage Florida citrus grower who owns Arapaho Citrus Management in Fort Pierce, Florida. He lifted bunches of yellow grapefruit with pink blush from the 2-year-old trees. “Ray ruby grapefruit on UFR-15 rootstock shows the kind of thing we are after in the Millennium Block trials. It’s a very nice fruit—very high quality—excellent performance for a young tree,” said Spyke.  “The tree has two blooms, a regular bloom and a late bloom. We will capture data from both blooms.”

    At a second location, where white grapefruit trees grow, Chris Hernandez showed an attendee a tree that produces sweet grapefruit. Hernandez is a UF horticulture undergraduate student and an agricultural assistant at IRREC.

    “My favorite grapefruit is Seedless Surprise. The variety is super sweet, the best flavor in a grapefruit I have experienced. And the trees tolerate citrus greening well,”Hernandez said.

    At another grove position, viewers gathered around Ken Gioeli, UF/IFAS Extension St. Lucie County Natural Resources Agent, to learn about invasive, venomous, and harmless snakes that may be found in the grove. Gioeli recommends growers to be aware of four venomous snakes found in the Indian River District and how they can increase safety. He urged visitors to report Burmese pythons with a mobile application, I’veGot1.

    Several longtime citrus growers were surprised to find some varieties in a condition they did not expect.

    “There are some variations in the rootstocks,” said Matt Hamilton. He, along with his family, own Hamilton Grove Services, Inc., in St. Lucie County. “I am surprised that some of the rootstocks I expected would do well are not looking too good, but a few of the UF rootstocks look good.”

    “Our family has been in the business since the 1960s,” said Mark Hamilton. “We are grapefruit growers, and we want to stay in business.”

    Growers recall many of the Indian River District’s citrus production challenges. Freezes, insects, and diseases have caused setbacks and the scion rootstock combinations may bring a comeback.

    “We need to make sure the trends we see today are consistent as time goes on. Next year’s data should be much more enlightening,” said Spyke.

    “The approach we are taking to breeding is to find tolerant scions and rootstocks that impart tolerance to the scion. Those combinations will be less expensive to grow and will produce larger crops of good wholesome fruit and those two factors will allow growers to make a good profit in the future. The data will be applicable to any variety growing anywhere in the state, including processed fruit.”

  • Tomato Trade with Mexico could Cost US Growers $250M a year

    As Mexico increases tomato exports across the world, including to the United States, prices plummet for American growers. That practice could cost American growers as much as $252 million per year — or 27% in revenue — if imports from Mexico increase by 50% in coming years, based on historical trends, new University of Florida research shows.

    That’s a huge loss for American farmers, who produced 1.3 billion pounds of fresh tomatoes in 2020, less than one-third the harvest from the year 2000.

    That decline is due to competition from Mexico and other challenges, said Zhengfei Guan, an associate professor of food and resource economics at the UF Institute of Food and Agricultural Sciences.

    Zhengfei Guan, a UF/IFAS associate professor of food and resource economics at the Gulf Coast Research and Education Center, studies tomato trading and its impacts on American growers, among other areas of research.

    Guan just published a study on the consequences of intensifying Mexican competition for American growers. The market positions of Mexican and domestic tomato industries completely reversed over the past 20 years. Mexico now dominates the U.S. market, with three times more market share than the domestic industry. That change sparked Guan’s interest in pursuing the new study.

    “The two countries had a series of trade disputes over fruit and vegetables recently,” he said. “One reason is that surging imports from Mexico boosted by subsidies have depressed prices, and American growers are quickly losing market shares.”

    “The findings from our study will provide tomato producers and policy makers with important insights on the challenges and the sustainability of the U.S. tomato industry,” Guan said.

    In his study, Guan measured the potential losses the U.S. industry will sustain as a result of the increasing imports from Mexico, given the steep growth over the years. As a frame of reference, the volume of imported tomatoes from Mexico increased by about 60% over the years 2009-2019.

    Results of Guan’s research show that prices of domestic tomatoes are particularly sensitive to imports from Mexico in an increasingly saturated market. The imports are especially damaging to the Florida tomato industry which has about $400 million in sales and has the same harvest seasons as Mexico.

    The trade deficit complicates matters for farmers in several commodities – not just tomatoes. Specifically, fruit and vegetables — such as tomatoes, strawberries, peppers, cucumbers and melons – accounted for 50% of the total U.S. agricultural imports from Mexico in 2020, according to the U.S. Department of Agriculture. “But all may not be lost, if the US fruit and vegetable industry could revolutionize the production technology,” said Guan. “Mechanization or automation will be a game changer and is the future for this labor-intensive industry.” — By Brad Buck, University of Florida Institute of Food & Agricultural Sciences

  • Giving Strawberry Growers a Ray of (UV) Light at the End of Their Pest Tunnel

    For a few years, University of Florida (UF) plant pathologist Natalia Peres has used an ultraviolet light system to thwart strawberry pathogens. Peres even published a study this year that showed the system helps control powdery mildew. Two fellow researchers with the UF Institute of Food and Agricultural Sciences (UF/IFAS) have now used the same robotic UVC applicator to show that it works well to slow the spread of one strawberry pest, but not a second.

    The three scientists and others at UF/IFAS are trying to tamp down pests and diseases for the strawberry industry. Joseph Dean Montemayor — working under the supervision of entomology assistant professor Sriyanka Lahiri — focused on whether a system that uses UVC radiation can control mites and thrips.

    Field technician Marissa Cassaway and master’s student Joseph Montemayor examine strawberries treated with UVC radiation at the Gulf Coast Research and Education Center (photo by Sriyanka Lahiri, UF/IFAS).

    They also studied whether UVC would interfere with biological control efforts of mites or thrips, both of which cause significant fruit loss if left untreated. In this case, they examined whether radiation would kill the predatory mites that eat these pest mites and thrips infesting strawberries.

    Results indicate that the eggs of the predatory mites, just like those of spider mites, die after irradiation with UVC. This indicates that biological control through predatory mites can be most effective only after a strawberry crop is treated with UVC radiation, rather than irradiating strawberries while the predatory mites are present in the field simultaneously.

    The research, part of Montemayor’s recently completed master’s thesis, shows that the system works well to control spider mite eggs but not chilli thrips. Specifically, the dosage of UVC radiation applied to strawberry plants in the field mostly suppressed spider mite eggs from hatching but did not deter chilli thrips infestations, said Lahiri, a faculty member at the Gulf Coast Research and Education Center (GCREC).

    The study’s results will become part of an integrated pest management system to help strawberry growers.

    “This information is useful to the strawberry growers of Florida, who have to constantly battle with chilli thrips and spider mites,” Lahiri said. “Also this information is relevant to strawberry growers across the world, industry partners and the small-fruit crops research and Extension community.”

    Montemayor, who will graduate in August with a master’s degree in entomology and nematology from the UF/IFAS College of Agricultural and Life Sciences, planted new UF/IFAS strawberries including ‘Florida Brilliance,’ ‘Florida Radiance’ and ‘Sweet Sensation’ in fields at GCREC.

    For his thesis, Montemayor also studied the potential impact of UVC radiation on predatory mites. Strawberry growers currently use a mite known as Phytoseiulus persimilis to keep the twospotted spider mite from harming their fruit, Lahiri said. Montemayor exposed this adult predatory mite to the same dose of UVC that was effective in  suppressing spider mite eggs.

    He found that P. persimilis remained unaffected and was able to actively feed on spider mite eggs.

    “Thrips and spider mites are the most economically damaging species affecting strawberry production in Florida,” Lahiri said. “Even though there is overwhelming reliance on the use of synthetic insecticides and miticides to manage these pests, biological control agents such as predatory mites can be effective in integrated pest management in strawberry. Another way is to use UVC irradiation, applied after sunset, to manage these entomological pests along with strawberry pathogens. Both these pest management tools can be used complementary to each other.”

    Lahiri, Peres and vegetable entomologist Hugh Smith, all faculty members at GCREC, served as members of Montemayor’s master’s thesis committee. — By Brad Buck, University of Florida Institute of Food & Agricultural Sciences

  • Are Finger Limes Just Another Fad?

    There has been growing hype around finger limes from citrus growers, the retail sector, and their customers. Growers are particularly interested in this market as disease pressure such as citrus greening and international competition have made other citrus and fruit markets less appealing. However, many are concerned that finger limes are just a fad and the markets will eventually crash as consumers move on to the next cool food trend. Our research at the University of Florida is examining these markets to determine the potential for growers in Florida and throughout the U.S. to take advantage of the emerging finger lime market.

    Finger limes are known as the “citrus caviar,” because of their unique compressed, round juice vesicles that are distinct from other citrus crops’ delicate, tear shaped fruit sacs. This feature combined with its bright colors and tangy flavor make finger limes a great garnish used in high end restaurants and as a perfect accent to a cocktail. As more and more chefs, bartenders, and suppliers in the hospitality industry become familiar with the fruit, they are falling in love with them and demand for finger limes is rapidly growing.

     Many growers and suppliers of finger limes are hopeful that the demand for this fruit will expand beyond the hospitality sector to mass markets, as consumers across the U.S. and around the world become more familiar with the fruit. Finger limes are not only resistant to greening that plagues orange and other citrus production but also have traditionally been grown using few agrochemical inputs. So, there are expectations that organic markets could provide an additional premium for this fruit. Some research has also pointed out the high prevalence of antioxidants in the fruit, providing finger lime growers and suppliers with potential to enter health food markets.

    This fruit, which is native to Australia, has only in the last several years become commercially available to growers across the US, after first having been cultivated in California in late 1960s. In fact, nearly all of the current production in the U.S. is in central and southern California and the big island of Hawaii. There are only about 15,000 trees, which are owned by less than a dozen growers. So, there is room to expand production especially by Florida growers, who supply East Coast markets. Prices are quite elevated for the fruit; for instance, during the spring of 2020 finger limes were priced at $32 for 80 grams or 8 limes on Amazon or $18 for 9 to 10 finger limes from one of the only suppliers in South Florida. Questions remain whether these prices will remain elevated as more and more growers enter the market.

    Over the next two years, we at the University of Florida will be exploring the potential for finger limes in these markets and how to develop inclusive supply chains to improve the participation of all growers in them. We will hold taste testing panels and interviews with suppliers, chefs, and bartenders at trade fairs to introduce them to the product, gauge their interest in the fruit, and estimate their willingness to pay for finger limes. The analysis of this research will allow us to estimate the potential demand of the fruit and how many growers could participate in this market. Additionally, we will examine the supply chain to determine which factors need to be addressed to improve growers’ access to these growing markets. Please be on the lookout for further updates as we examine the potential growers to tap into growing finger lime markets and determine what can be done to sustain the demand for them. — By Trent Blare (tblare@ufl.edu), Assistant Professor in Food Resource Economics, University of Florida

  • White Strawberry One of Two New Varieties Ready for Harvest Season

    Enjoy the following article featuring two new strawberry varieties out of the University of Florida that may prove to be of value to West Coast growers in the near future.

    A white strawberry? Not red? Yes, you “read” that right. And it smells a little like a pineapple. It’s also novel in that it’s the first white strawberry to go to market in the United States. Just in time for the west-central Florida strawberry harvesting season, which runs from now until the end of March, University of Florida Institute of Food & Agricultural Sciences (UF/IFAS) is releasing not one, but two new varieties – and the white strawberry is one of them. The other: another cultivar that UF/IFAS’ primary breeder says tastes oh-so-good.

    Neither variety has a name yet. They’re known by numbers, which is typical early in the cultivar-release process. So far, they’re known as ‘FL 16.78-109’ (the white strawberry) and ‘FL 16.30-128’ (the red strawberry), said Vance Whitaker, a UF/IFAS associate professor of horticultural sciences and a strawberry breeder.

    “Because the white strawberry is being test-marketed this year, there has been a lot of interest in it,” said Whitaker, a faculty member at the Gulf Coast Research and Education Center. In fact, a grower told Whitaker that some chefs like the new fruit.

    When it’s ripe and ready to eat, it is white inside and out, with a slight pink blush on the skin and red seeds, he said. “The flavor is very different from a typical strawberry, sweet but with a pineapple-like aroma,” Whitaker said. “White strawberries have been popular for some time in Japan, but this is expected to be the first white strawberry on the market in the United States.”

    You can find white strawberries in nature, he said. Breeders have harnessed this naturally occurring trait, crossing white strawberries from the wild with modern strawberries to create something different in both appearance and taste.

    Here’s how the white strawberry came about.

    In 2012 strawberry seeds from Japan were sown at the University of Florida, and a few small plants recovered. The seeds were sown, and a few small plants were recovered. The pollen from these plants were crossed with a Florida variety. The seedlings from this cross-produced fruit that ranged from white to pink to red, Whitaker said.

    “Commercial trials have been promising so far,” he said. “Pickers can tell when the fruit is ripe when a slight pink blush develops on the side of the fruit that is most exposed to the sun, and when most of the seeds turn red. By 2022, these new white strawberries should be available in U.S. grocery stores. They will probably be marketed as “pineberries” because of the pineapple aroma.”

    Whitaker also touts the consistently even red color and conical shape of the new red variety, making the fruit more attractive.

    Here’s how the colors differ in the two strawberries: The red from a typical strawberry comes from pigments called anthocyanins. White strawberries produce much lower amounts of these compounds in their flesh than red strawberries, Whitaker said.

    As harvest arrives, farmers will welcome the new red and white strawberries from UF/IFAS, Whitaker said. UF/IFAS researchers and the Florida Strawberry Growers Association estimate strawberries generate about $300 million annually for those who farm them.

    Out of the 10,000 acres of strawberries in west-central Florida, the new red strawberry may occupy as much as 300 acres in Florida during the 2021-2022 season, and if it continues to perform well, that number could grow.

    The white strawberry, or “pineberry,” will be grown on fewer acres since it is a new specialty product. It will take time for farmers to become comfortable growing it, and it will also take time to educate consumers about this new fruit.

    “The new red strawberry is notable for its outstanding flavor,” Whitaker said. “Because of its high sugar level, it tastes somewhat similar to (another UF/IFAS variety called) Sensation®, which is currently one of the leading varieties in Florida, yet with a more intense flavor due to the fruit’s higher acid content.” — Brad Buck, University of Florida Institute of Food & Agricultural Sciences

    Cristina Carriz, UF/IFAS

  • Progress Toward Greening-Resistant Citrus Trees

    University of Florida scientists achieved a major milestone in their quest to develop a citrus greening-resistant tree by sequencing the genome of a fruit plant that’s a close cousin to citrus trees. You’d need to print 54,000 pages of copy paper to see the complete genome sequence. But within it, scientists believe they’ve found genes to lay the groundwork to make citrus more tolerant and even resistant to certain diseases, including citrus greening.

    UF/IFAS researchers sequenced the genome from trifoliate orange, in collaboration with scientists from the University of California at Berkeley, the U.S. Department of Energy’s Joint Genome Institute and UF’s Interdisciplinary Center for Biotechnology Research. The new genome will help those who breed new citrus trees that will survive under today’s challenging conditions, including invasive pests, viruses and changing climates. Their research provides a powerful new tool to control the deadly consequences of the greening disease, which has severely damaged the state’s multibillion dollar-a-year citrus industry.

    “Very importantly, trifoliate orange and its hybrids have genes that can confer high tolerance to citrus greening and resistance to the Asian citrus psyllid, the insect that transmits greening to citrus,” said Zhanao Deng, a professor environmental horticulture and a senior author on the new UF/IFAS-led study. “This genome can be used as a reference template to sequence widely used trifoliate orange hybrid rootstock varieties.”

    “Most people – even citrus growers – rarely see trifoliate orange. This is because they usually are the rootstock part of the tree, mostly underground,” said Fred Gmitter, a UF/IFAS professor of citrus breeding genetics and a co-author on the study.

    Trifoliate oranges or their hybrids are grown at nurseries, and farmers use them as rootstock to grow the citrus that’s above ground. Trifoliate orange and its hybrids were used as the rootstock for more than three million citrus trees in Florida alone in 2018-2019, UF/IFAS researchers say.

    Trifoliate orange and its hybrid rootstocks accounted for 82% of the top 20 rootstocks used in the 2018-2019 citrus propagation cycle in Florida.

    “Our trifoliate orange genome will allow scientists to develop new tools that can more speedily transfer beneficial genes into sweet oranges, grapefruit and breeding of new scion cultivars, which grow above the ground,” Deng said.

    “Releasing the first trifoliate orange genome can be valuable for our citrus gene-editing efforts,” Gmitter said. Scientists are using gene editing to produce canker-resistant and greening-tolerant citrus.

    “Because of our high-quality genome, re-sequencing of trifoliate orange hybrid rootstock varieties will be much easier, much quicker and much more cost-efficient,” said Deng. “Re-sequencing will enable development of new breeding tools, such as DNA marker-based selection, genomic selection of new rootstock varieties with resistance and tolerance to citrus greening, citrus tristeza virus and citrus nematodes. The new varieties might give higher yield and fruit quality.”

    Citrus breeders want to introduce desirable genes from trifoliate orange into sweet orange, grapefruit and other varieties. It took decades to produce the first citrus scion variety (‘Sun Dragon’) from crossing trifoliate orange and transferring some of its genes across multiple generations into sweet orange. With this new information from genome sequencing, that timeline can be dramatically reduced.

    This project was funded by two grants from the Citrus Research and Development Foundation (CRDF) and a grant from the USDA/NIFA Citrus Disease Research and Extension (CDRE) program.

    To see a video about the research and its implications, click here. — By Brad Buck, University of Florida