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Category: VSCNews magazine

  • Stanley Culpepper: A leading voice for growers

    By Clint Thompson

    When University of Georgia (UGA) Cooperative Extension weed agronomist Stanley Culpepper speaks, Tift County grower Bill Brim listens. After more than two decades of Culpepper providing expertise regarding more than 20 different vegetable crops, there’s no reason for Brim not to pay attention.

    “He’s a great young man. He’s a hard worker and tries to get things done. He’s the best one out at the (experiment) station, as far as I’m concerned,” says Brim, co-owner of Lewis Taylor Farmers in Tifton, Georgia.

    Culpepper’s accomplishments are a big part of why growers like Brim have confidence in what the scientist says. A professor in the UGA Crop and Soil Science Department, Culpepper is a world-renowned scientist at one of the leading agricultural colleges in the country and has had a lot to say over his 20-plus years at the Tifton campus.

    Culpepper’s team is improving tactics for vegetable growers to better manage weeds. In the last couple of years, he has been very active in fruiting vegetables, like tomato, pepper and eggplant; cucurbits, like watermelon, squash, cantaloupe and cucumber; cole crops, like broccoli and cabbage; and leafy greens, like collard and mustard; as well as carrots.

    Whether it’s researching alternatives to methyl bromide or developing management strategies for overcoming palmer amaranth weeds, Culpepper has had far-reaching impact in commodities across the world.

    “My team’s research efforts have always and will always follow the needs of our growers, which are of course, very diverse,” Culpepper says. “Developing alternative systems to methyl bromide that our farmers continue to rely on today was certainly among our more impactful work. I also think it was my favorite personal project. That effort was so large that I had an opportunity to work with growers for an extended period of time early in my career. Those growers really helped teach me how to grow vegetables on plasticulture. And of course, what good is research if the researcher can’t grow a crop like a grower?”

    UGA 3-WAY

    Culpepper’s work with methyl bromide alternatives is considered among his most impactful contributions as a scientist. For decades, Georgia vegetable producers relied on methyl bromide as a soil fumigant to control weeds, insects and nematodes. It was phased out in the mid-2000s, though, when the Environmental Protection Agency deemed it harmful to the ozone.

    Culpepper devoted almost 10 years of research to finding suitable alternatives. Brim said an effective alternative that Culpepper was responsible for was the UGA 3-way system that implements Telone II, metam sodium and chloropicrin.

    “What he did was just a tremendous help for us as far as developing a new product that we could use” for weed, fungus and nematode control, says Brim. “Without that, we’d probably be out of business. Methyl bromide was such a forgiving chemical as far as helping us develop nematicide programs and weed control and disease control. When we lost methyl bromide, we thought we were just done. Stanley did research here on the farm on the 3-way … two years before we actually started using it completely before methyl bromide was taken away from us. We really didn’t know until years later (how effective it was going to be), and now we’re still using the 3-way.”

    EXPANDING HERBICIDE LABELS

    Another area Culpepper has had a major impact on is the development of new herbicide tools for vegetable growers. His efforts have led to more than 34 new herbicide uses in various vegetable crops for Georgia farmers. He has also assisted growers in other states to obtain these labels.

    “I absolutely love finding new effective herbicides for a vegetable grower and getting them labeled in a way that is safe for the user, the crop and our environment. Of course, this accomplishment is the result of an amazing team of people working together from the University of Georgia, industry, IR-4, The Georgia Department of Agriculture and the U.S. EPA,” says Culpepper. 

    DESTINED FOR AGRICULTURE

    Culpepper was destined for a career in agriculture. He grew up on a bicentennial family farm in North Carolina where his family produced corn, cotton, peanuts, soybeans and wheat. So much of his childhood influenced every step of his career. Culpepper remembers those hot summer days of pulling weeds when he was very young. He even recalls chopping them down with a hatchet as some were twice as big as he was.

    “I thought I might be able to make a difference studying weed science,” Culpepper remembers. “Hopefully, I have.”

    He received a bachelor’s degree in agronomy and his master’s and doctorate degrees in weed science from North Carolina State University.

    Culpepper began his professional career at UGA as a cotton, vegetable and small grain weed scientist in 1999 and continues with those same responsibilities today.  

    ACCOMPLISHED CAREER

    Culpepper’s awards and accomplishments speak volumes about how his colleagues view his work. He has been a guest speaker at more than 300 events across the globe; 686 Extension county meeting presentations and 66 in-service Extension trainings. He has authored or co-authored 106 refereed journal articles, four book chapters, 406 abstracts for presentations, 223 Extension publications and 222 newsletters/blogs.

    Culpepper has received 31 professional awards. Some of the highlights include:

    • Donnie H. Morris Award of Excellence in Extensionfrom the Georgia Fruit and Vegetable Growers Association (2003)
    • Montreal Protocol Award from the EPA for assisting in the preservation of the ozone layer (2010)
    • Walter Barnard Hill Award for Distinguished Achievement in Public Service and Outreach from UGA (2014)
    • Southern Region Excellence in Extension Award from the Association of Public and Land-grant Universities (2016)
    • Walter Barnard Hill Distinguished Public Service Fellow Award from UGA (2019)

    In addition, Culpepper is currently serving a third term as a member of the Agricultural Science Committee of the U.S. EPA Science Advisory Board.

    Culpepper attributes his success to working with others. “Success is really driven by cooperation, whether that is with Extension agents, farmers, consultants, industry partners, regulators, or usually with all of these groups. As we continue to move forward in agriculture, this is a priority for our sustainability,” Culpepper concludes.

  • Sneak Peek: December 2020 VSCNews Magazine

    By Ashley Robinson

    Georgia growers may recognize the man on the cover of the December issue of VSCNews Magazine. Stanley Culpepper, University of Georgia (UGA) Cooperative Extension Weed Agronomist, has more than two decades of experience working with vegetable crops. Learn more about Culpepper’s expertise and his impact on the vegetable industry in the magazine.

    Also discussed in the magazine are current issues facing growers in the Southeast. This part of the country is paradise for root-knot nematodes, one of the most rapidly spreading pests. Johan Desaeger, an assistant professor at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Gulf Coast Research and Education Center, discusses management strategies for vegetable growers.

    Amid the COVID-19 pandemic, it’s crucial to educate farm owners, supervisors and workers on how to best do their jobs under pandemic conditions while preserving their health and livelihood. Kimberly Morgan, an associate professor and Extension economist at the UF/IFAS Southwest Florida Research and Education Center, shares how the UF/IFAS Farm Labor Supervisor COVID-19 Safety Training program has worked to protect Ag workers during the pandemic.

    Any fruit or vegetable grower knows that untimely freezes can cause tremendous problems for their crops. Pam Knox, agricultural climatologist, and Tim Coolong, both UGA professors, share freeze-protection methods for fruit and vegetable crops.

    Additionally, Taylor Langford, a UF/IFAS produce safety education and training specialist; Matt Krug, statewide UF/IFAS food science Extension agent; and Michelle Danyluk, a UF/IFAS professor, come together to discuss the Food Safety Modernization Act’s Produce Safety Rule (PSR) which highlights the need to reduce risks associated with agricultural water that will contact fresh produce.

    Finally, there are new BMP record-keeping requirements for Florida growers. Ajia Paolillo, a UF/IFAS Extension multi-county citrus agent based in Arcadia, has a Q-&-A style article featuring Matt Warren, environmental manager with the Florida Department of Agriculture and Consumer Services Office of Agricultural Water Policy in Hardee County to answer the most common questions growers have regarding the new requirement.

    If you would like to receive future issues of VSCNews magazine, click here.

  • Mulch Improves Water Conservation in Vegetable Production

    Sweet onions are shown growing in Tifton, Georgia, with two types of mulch: organic (wheat straw mulch) on the left and inorganic (plastic mulch film) on the right.

    By Juan Carlos Díaz-Pérez

    For centuries, horticulturists have modified the crop microenvironment to extend the production season and enhance crop growth, yield and quality. Some of the techniques to achieve environmental modification include the use of mulches, high tunnels, greenhouses, etc.

    Mulches are widely used in both conventional and organic vegetable production. According to Wikipedia, “a mulch is a layer of material applied to the surface of soil with the goal of conserving soil moisture, improving fertility and health of the soil, and reducing weed growth.”

    Mulch may be organic (straw, leaves, cover crop residue, newspaper, wood chips, etc.) or inorganic, such as plastic film. Mulch effects on crops may vary depending on different factors.

    Factors affecting organic mulches include source of organic material (plant or animal), size of the particle, thickness of the mulch (amount applied) and age of the material. Factors affecting plastic mulch films include color, thickness, composition and permeability.

    In a vegetable crop field, soil water may be: 1) evaporated from the soil, 2) evaporated from the surface of the leaves of the crop, in a process called transpiration, 3) lost from surface runoff or 4) lost by percolation. In this article, we will focus on ways to improve soil water conservation.

    SOIL WATER EVAPORATION

    Both organic mulches and plastic mulch films act as barriers to water evaporation from the soil. These two types of mulches differ, however, in how they diminish soil water evaporation.

    In bare soil, water tends to evaporate from the soil. Soil water evaporation is proportional to the evaporative demand. Evaporation increases with increasing air and soil temperatures and decreasing relative humidity.  The rate of soil water evaporation also decreases as the soil water content decreases.

    According to the Food and Agriculture Organization of the United Nations, organic mulches may reduce soil water evaporation from 40 to 90 percent relative to bare soil. A thickness of 2 to 4 inches is effective in reducing evaporation. Soil evaporation tends to decrease with decreasing particle size of organic residues.


    Plastic mulch films are, in general, more effective in reducing soil water evaporation compared to organic mulches. Plastic mulch films differ in permeability to gases due to differences in film composition. For example, virtually impermeable film and totally impermeable film provide greater fumigant retention compared to low-density and high-density polyethylene film. With respect to soil evaporation, however, all plastic mulch films seem to be effective in conserving soil moisture.

    Physical damage or deterioration decrease the effectiveness of a plastic film to reduce soil water evaporation. Biodegradable mulches may be more prone to rapid deterioration compared to plastic mulch films.

    RAINFALL PENETRATION INTO SOIL

    Water-use efficiency increases when the crop uses rainfall water. Although organic mulches reduce soil evaporation, they allow for water penetration to the soil after a rainfall event. In fact, by reducing water flow through the soil surface and improving soil structure, organic mulches improve the water penetration to the soil and reduce soil runoff compared to bare soil.

    In contrast to organic mulches, plastic mulch films are impermeable to liquid water. Thus, they do not allow rainfall water penetration into the soil covered by the film. Rainwater that reaches the plastic film flows to the soil area between the beds and may result in soil runoff and soil erosion.

    In conclusion, both organic mulches and plastic mulch films are useful tools that help growers conserve soil moisture and increase irrigation efficiency.

  • New Findings on Growing Hemp in Florida

    By Tory Moore

    As the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Industrial Hemp Pilot Project research continues, growers around the state have begun growing hemp on their own farms. Researchers from the UF/IFAS Mid-Florida Research and Education Center (MREC) in Apopka have important considerations for Florida growers contemplating or currently growing hemp. Research lessons learned and new findings are the focus of this article.

    FLOWERING REQUIREMENTS

    Understanding hemp genetics, specifically flowering requirements, before you plant is vitally important.

    Hemp is predominantly a short-day, photoperiod-sensitive plant. In controlled environments like greenhouses, hemp is commonly grown under 18 hours of light to keep plants in a vegetative phase and then transitioned to 12 hours of light to initiate flowering. Supplemental lighting is necessary to maintain plants in a vegetative state when natural daylength is below the daylength that initiates flowering. Photoperiod requirements vary among hemp varieties and cultivars.

    Genetics determine whether flowering in a particular variety or cultivar is daylength dependent or daylength neutral (known as autoflowering).

    Daylength-dependent varieties and cultivars flower when daylength shortens to a critical threshold and triggers flowering. This is somewhere between 12 to 15 hours of daylight, depending on the variety or cultivar. Florida has between 13 to 14 hours of daylight on the longest day of the year, the summer solstice on June 21, which limits optimal planting time to within a few weeks of the solstice. Beyond optimal planting dates, plants can reach a desirable size if grown vegetatively under lights for three to six weeks prior to transplanting or removal from supplemental lighting. However, this is dependent upon the growth rate and plant architecture of the variety or cultivar.

    Daylength-neutral or autoflowering varieties and cultivars will flower after a specific maturity time, commonly 30 to 50 days after sowing. Autoflowering hemp plants are generally smaller and can be planted at higher densities, with some reports of seeding rates of up to 26,000 plants per acre.

    Take time to learn what the early stages of flowering look like so you can accurately track flower development. Flower bulking is noticeable starting around two to three weeks.

    Weekly or twice weekly, sampling of upper plant flowers and other plant tissue should be conducted after flowering has begun. Sample to ensure the crop does not exceed the 0.3 percent limit for total Delta-9 THC, commonly known as “going hot.” High floral density can be achieved by six to eight weeks after floral initiation.

    This illustration is representative of one cultivar’s flowering process. The transition can appear different across cultivars. Source: UF/IFAS Industrial Hemp Pilot Program

    Most high-cannabinoid hemp cultivars are dioecious, meaning plants are either male or female. Only female hemp plants produce desirable flowers and high-cannabinoid extract. When fertilized by male pollen, female plants produce seeds and produce less oil. It is critical to determine plant sex when cultivating essential oil-type hemp to prevent accidental production and pollination by male plants, which would reduce high-cannabinoid production ideal for CBD and CBG products.

    PEST MANAGEMENT

    Consider pest management early and evaluate pest pressure in your hemp crop often.

    You will encounter pests within your hemp crop. Commonly found pests include aphids, mites, arthropods (grasshoppers) and worms (tobacco budworm, corn earworm and beet armyworm).

    Weekly scouting for pests is recommended with special attention being made during flowering. Worm pressure is most noticeable during flowering and can devastate a hemp crop. If you identify your plants transitioning, be prepared for worm pressure.

    Pesticides available for use in hemp are limited. UF/IFAS recommends testing approved pesticides on a few plants to see if the products cause harm before treating the entire crop. Growers will want to be prepared to spray as soon as they see a need, so conducting this testing before a problem arises is critical. Since there are a lack of conventional pesticides available for use in hemp, be sure to know what pest control products are approved by the Florida Department of Agriculture and Consumer Services.

    Fungal issues in hemp have been observed both in greenhouse and field trials.

    IRRIGATION AND FERILIZATION

    Hemp needs adequate water for optimal growth but does not like “wet feet.” Hemp sitting in water for just a day or two can promote virulent fungi and kill plants.

    Selection of appropriate growth media or field space is critical to keep plants healthy. Keep in mind that hemp cultivars have varying water demands and tolerance. Dialing in your irrigation will be critically important for success.

    Preliminary findings for greenhouse-grown hemp suggest that plants can be grown in a wide variety of substrates. Hemp in container production seems to favor substrates with greater porosity (air space). Plants perform poorly in substrates that stay too wet, as root rot has been observed in other substrates.

    If fertigating, low fertigation on a consistent basis is advised to reduce leaching through the soil.

    In potted studies, significant losses were seen at soil electrical conductivity of 1.9 or greater. If fertigation is not possible, consistent results can be achieved with appropriate amounts of granular fertilizer.

    ADDITIONAL ADVICE

    If taking vegetative cuttings of the crop, the selection of proper rooting media is critical. Always use a rooting hormone to increase rooting success. Hormone concentrations that are too high can reduce rooting success; 1,000 parts per million indole-3-butyric acid tends to work well.

    Florida has unique growing conditions and pressures that make producing any new crop a challenge. Along with UF/IFAS Industrial Hemp Pilot Project information, rely on those successfully growing hemp in your area to provide data-driven and specific production advice. If you have not yet begun to grow hemp, consider the rules and regulations as well as the inherent risks of growing any new crop. 

    Hemp production lacks a body of knowledge validated by years of scientific research and data, much of which the UF/IFAS Industrial Hemp Pilot Program actively seeks to develop. UF/IFAS researchers recommend growers make hemp cultivation and management decisions and choose genetics based on information appropriate to their region and backed by science.

    UF/IFAS Extension agents across the state are available for support and to answer questions tailored to your region and farm. The UF/IFAS Industrial Hemp Pilot Project website (programs.ifas.ufl.edu/hemp) is updated regularly with the latest research results and ways to learn more about growing hemp in Florida.

    Acknowledgments: Steven Anderson, Brandon White, Brian Pearson and Roger Kjelgren contributed to this article.

  • Smart Irrigation Tools for Blueberry Growers

    Figure 1. A: The University of Georgia Smart Sensor Array (UGA SSA) node is installed in blueberries. The electronics are housed in the white PVC container. The spring allows the antenna to bend when farm vehicles pass overhead. B: The UGA SSA sensor probe integrates three Watermark sensors and can be customized to any length.

    By Vasileios Liakos

    One of the goals of the University of Georgia College of Agricultural and Environmental Sciences (UGA CAES) is to develop new irrigation methods and tools for crops. Researchers, including myself, Erick Smith, George Vellidis and Wes Porter, have been developing smart irrigation scheduling tools for blueberry growers in Georgia since 2015. Smart irrigation is a new method of irrigation that uses technology and information to make more accurate and faster decisions.

    UGA has developed two smart irrigation tools for blueberries — the UGA Smart Sensor Array (SSA) and the Blueberry App.

    SYSTEM RECORDS SOIL MOISTURE

    The UGA SSA is a system that records soil moisture within fields. It consists of a monitoring system, a commercial server that receives soil moisture data wirelessly, and a website that presents soil moisture data and recommends irrigation rates. The monitoring system consists of smart sensor nodes and a gateway. Each node has a circuit board, a radio frequency transmitter, soil moisture sensors, thermocouple wires and an antenna (Figure 1a). Each node accommodates two thermocouples for measuring temperature and a probe that consists of up to three Watermark® soil moisture sensors (Figure 1b).

    “Soil moisture sensors record soil water tension, and we realized very soon that farmers could not make irrigation decisions based on the sensor readings. It was necessary to convert sensor readings into amount of irrigation,” said UGA precision agriculture specialist George Vellidis.

    To overcome this problem, we utilized soil properties and a model to convert soil water tension numbers into inches of irrigation that is needed to saturate the soil profile. Additionally, farmers can see in real time their soil moisture data to make irrigation decisions for each location in fields using a web-based interface that was developed by UGA.

    IRRIGATION SCHEDULING APP
    Figure 2. Left: The main screen of the Blueberry App tells growers how many hours they need to run their irrigation systems and how many gallons they are going to use. It also allows them to check accumulated rainfall from the past seven days and the expected crop evapotranspiration for the next seven days. Right: Blueberry growers do not have to check the app daily since it notifies users if there is rain at the field and how much irrigation they need to apply.

    Blueberry growers can also use the Blueberry App on their smartphones to schedule irrigation (Figure 2). The app runs a model that uses reference evapotranspiration (ETo) data and the Penman-Monteith equation to calculate the irrigation needs of blueberries.

    The innovation of the Blueberry App is that it is programmed to receive forecasted ETo data for the next seven days for every location in the United States from the Forecast Reference Evapotranspiration service of the National Oceanic and Atmospheric Administration. Precipitation data are received from the Georgia Automated Environmental Monitoring Network and the Florida Automated Weather Network (FAWN).

    UGA has developed a crop coefficient curve that shows the water needs of blueberries in Georgia every year. The goal is to include more coefficient curves from other states. This will be capable if more blueberry growers use the app.

    By knowing the total ETo for the next seven days and the crop coefficient values of the blueberries, the crop evapotranspiration of blueberries can be calculated, and irrigation events adjusted accordingly.

    EVALUATION OF SOIL MOISTURE SENSORS

    Another interesting project, involving soil moisture sensors and blueberries, began a few months ago. The objectives of the project are to 1) compare different commercially available soil moisture sensors in blueberry soil, 2) determine the accuracy of each type of soil moisture sensor in blueberries and 3) determine which soil moisture sensor type is best for use in blueberries.

    Figure 3. Field trials are testing four different soil sensor types in blueberry fields.

    The soil moisture sensors used in this project are Watermarks, Irrometer tensiometers, Aquachecks and Decagons (ECHO EC-5). The selection of these sensors was made based on their popularity in the United States. Table 1 shows advantages and disadvantages of different types of soil moisture sensors.

    This study takes place at a UGA blueberry farm in Alapaha and at two commercial blueberry farms in Alma and Manor. At each site, the four different soil moisture sensor types have been installed close to each other along the beds to collect data to meet the objectives of the project (Figure 3).

    Source: Practical use of soil moisture sensors and their data for irrigation scheduling by R. Troy Peters, Kefyalew G. Desta and Leigh Nelson, 2013, Washington State University.

  • New Disease Threatens Florida Strawberries

    By Natalia A. Peres

    Pestalotia fruit rot lesions on ripe fruit; symptoms are very similar to those of anthracnose fruit rot caused by Colletotrichum accutatum.
    Photo by UF/IFAS GCREC

    Pestalotiopsis is not necessarily new to strawberry. A strawberry fruit rot caused by Pestalotia longisetula (or Pestalotiopsis) was reported for the first timein Florida in 1972. However, the fungus has always been considered a secondary pathogen. But this was not the case during the past two strawberry seasons (2018–19 and 2019–20), when severe outbreaks were reported in Florida commercial fields. Root, crown, petiole, fruit and leaf symptoms were observed. Yield was severely affected, and several acres of strawberry fields were destroyed before the end of the season.

    University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) studies indicate that isolates from the recent outbreaks are more aggressive and may belong to a new species of the genus Neopestalotiopsis.

    Many growers consider the disease a new threat to strawberry production. Several questions are being asked: Where did this come from? Why is it so aggressive? How does it spread? What are the conditions for the spread? Will it survive in Florida fields? How can it be controlled? UF/IFAS researchers are working hard on trials to understand the new disease and develop best management practices to control it.

    SUSCEPTIBILITY AND SPREAD

    UF/IFAS studies found the disease apparently originated from other hosts around strawberry nursery fields. Thus, strawberry cultivars do not seem to have any immunity to it, and all cultivars that are currently grown commercially in Florida (Florida Beauty, Florida Brilliance, Florida Radiance and FL127 SensationTM) are susceptible.

    The fungus is favored by high temperatures (77 to 86º F) and produces spores on the surface of infected tissues that are spread by water. Extended rainy periods or overcast conditions with prolonged leaf wetness during the strawberry season, such as those that occurred last December, are problematic. To minimize dispersal from field to field, growers are advised to limit their operations (such as harvesting or moving equipment through fields) when plants are wet. Current studies are focusing on sampling other hosts and weeds around Florida strawberry fields during the off-season to determine whether the fungus could become endemic in Florida. 

    MANAGEMENT METHODS

    Growers want to know how to manage the disease, and many different fungicide products have been screened in the laboratory and evaluated in field trials at the UF/IFAS Gulf Coast Research and Education Center (GCREC). In the field trials, the fungicide pre-mix of fludioxonil + cyprodinil (Switch® 62.5 WG) and thiram (Thiram® SC) significantly reduced disease incidence.

    Only a few other fungicides that are not currently labeled for strawberry use were somewhat effective. Since the overuse of fungicide products can lead to increased selection for fungicide resistance, applications need to be limited to the maximum the label recommends, and research needs to continue to seek alternatives.

    For the upcoming season, growers should closely scout plants arriving from nurseries for leaf spot symptoms. Unfortunately, there are many leaf spot diseases that look alike, so it is important to get the correct diagnosis. If caught early and at low levels, removing the symptomatic plants from the fields is advisable.

    The current seasonal forecast is for La Niña, which is known to bring a warmer than normal and dry climate pattern to Florida and the Southeast. The dry weather during La Niña years is usually not conducive to fungal diseases such as pestalotia leaf spot as well as anthracnose and botrytis.

  • Coming Soon: New University of Florida Strawberry Varieties

    A new University of Florida Institute of Food and Agricultural Sciences strawberry release has excellent shape and flavor.

    By Vance M. Whitaker

    Two new strawberry selections have been approved for release by the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) and are in the commercialization process. Trade names have not yet been finalized but should be chosen in the next six months. For both, larger-scale testing will be conducted this fall, and commercial quantities will be available to Florida growers for the 2021–22 season.

    The first release is an early short-day variety with excellent fruit shape and quality. It has slightly lower November and December yields than Florida Brilliance but has had high January yields. It has excellent flavor, with taste panels ranking it equal to or even better than Sweet Sensation® Florida127, depending on the harvest date. It also has high Brix through the season, similar to Sweet Sensation® Florida127. The push for better flavor is an important pursuit for the UF/IFAS strawberry breeding program, so the team is very excited about the sensory qualities of this new release.

    A new white-fruited release from the University of Florida Institute of Food and Agricultural Sciences has a unique appearance and flavor. Photo by Cristina Carrizosa, UF/IFAS Communications

    The second release is a white-fruited strawberry. White-fruited varieties have been popular in Japan for some time, but this is expected to be the first such variety on the market in the United States. It has white internal and external color, with a pink blush on the sun-side and red achenes. The appearance of the pink blush and the achenes turning from green to red are the visual cues signaling that the fruit is ripe and ready to eat. The fruit are a little bit smaller than the other current varieties and are more similar in size to the fruit of Festival. The yield of this variety is about 75 percent of the current varieties grown in Florida, which are primarily Florida Brilliance and Sweet Sensation® Florida127.

    It is important to mention that new strawberry variety releases from UF/IFAS are exclusive to Florida growers for the first three years, but trialing can be conducted during this period with permission from the Florida Strawberry Growers Association.

    Regarding current varieties, Sweet Sensation® Florida127 (released in 2013) is fully available throughout the United States, while Florida Brilliance (released in 2017) is still exclusive to Florida for one more season. However, with permission, Florida Brilliance can be trialed outside of Florida in 2020 and will be fully available in 2021.

  • Problematic Pests of Florida Strawberries

    Stunted young trifoliates in the plant center (compact leaf mass). (Photos by Sriyanka Lahiri, UF/IFAS)

    By Sriyanka Lahiri

    Several arthropod pests occur in strawberries in Florida during the various stages of the crop cycle.

    Cyclamen mites (Phytonemus pallidus), if present, originate from strawberry nurseries as hitchhikers on transplants. Thankfully, a very small percentage of growers reported a cyclamen mite infestation during the strawberry season of 2019–2020.

    Soon after planting, armyworms (Spodoptera spp.), twospotted spider mites (TSSM, Tetranychus urticae) and the invasive polyphagous chilli thrips (Scirtothrips dorsalis) are typically found infesting plants.

    TSSM can also arrive as hitchhikers on transplants, occasionally. The presence of armyworms on young foliage becomes immediately evident due to feeding holes left by their biting-chewing mouthparts. Both TSSM and chilli thrips feed on foliage using their piercing-sucking mouthparts. TSSM produce webbing on the surface of the foliage and lay eggs on these webs. However, chilli thrips differ in their oviposition practices.

    The more devastating chilli thrips prefer feeding on the youngest open leaflets. Eggs are laid by the chilli thrips female into the leaf tissue using a saw-like ovipositor. This protects eggs from insecticides and predators. Both chilli thrips adults and larvae find refuge in concealed areas of the foliage, which makes them a very effective cryptic pest.

    As plants progress toward flowering and fruiting, more thrips species appear, such as western flower thrips (WFT, Frankliniella occidentalis), common blossom thrips (F. schultzei) and Florida flower thrips (F. bispinosa) in addition to chilli thrips. Of these thrips species, both chilli thrips and WFT cause significant economic damage and develop resistance to insecticides easily.  

    DAMAGE

    A cyclamen mite infestation can lead to severely stunted and crinkled leaves, aborted flowers, and bronzed and cracked fruits.

    Chilli thrips larvae and adult. (Photo by Joseph D. Montemayor, UF/IFAS)

    Chilli thrips cause necrosis at the site of feeding, which leads to darkening along the leaf mid-rib, followed by the spread of the dark coloration to lateral veins and petioles. Leaf bronzing, crinkling and deformation occurs during severe chilli thrips infestation.

    Severe thrips and cyclamen mite infestations lead to bronzed and cracked fruits that are unmarketable.

    An infestation of TSSM will lead to stippling of leaves initially. Uncontrolled TSSM populations become evident by the appearance of webbing.

    MANAGEMENT

    Management of cyclamen mites is best done with a preventive approach. Therefore, obtaining clean transplants is of utmost importance. Since all life stages of cyclamen mites show high mortality when exposed to hot water, a dip of frozen transplants into hot water at 111 °F for 10 minutes before planting may help. Alternatively, infested plants should be removed from the field.

    The most significant early-season strawberry pest that is currently posing a management challenge in Florida is the invasive chilli thrips. Conventional insecticides are being used to manage thrips pests, but there are several naturally occurring beneficial insects that could be used. These include predators such as the big-eyed bug (Geocoris spp.) and the minute pirate bug (Orius insidiosus). Additionally, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) greenhouse experiments using potted strawberry plants have confirmed the efficacy of the WFT predator Amblyseius swirskii as effective for suppression of chilli thrips larvae.

    An infestation of TSSM in open-field strawberries is best controlled by releasing the specialized predatory mite Phytoseiulus persimilis.

    Armyworms are effectively managed by early-season application of biological insecticide formulations of Bacillus thuringiensis, subsp. kurstaki.

    Pesticides registered for various strawberry pests are listed in the UF/IFAS Vegetable Production Handbook of Florida (https://edis.ifas.ufl.edu/pdffiles/CV/CV13400.pdf). It is important to select pesticides that are least harmful to beneficial arthropods, rotate modes of action and follow the label.

  • Florida Hops Show Potential

    By Shinsuke Agehara

    Hops are grown on various sized trellises at the Gulf Coast Research and Education Center in Wimauma, Florida.
    Photo by Shinsuke Agehara

    Craft beer brewed with Florida hops sounds very attractive. But can hops be grown in Florida? Will the crop produce high yields? The most important question is: Will it be profitable?

    There are lots of rumors, myths and hype about growing hops in the Sunshine State. That’s probably because hops have never been grown commercially in Florida and other subtropical regions — at least not on a large scale. There simply was not enough information. The profitability of Florida hops is still unknown, but a lot of information is now available from ongoing research conducted at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Gulf Coast Research and Education Center (GCREC).

    In 2016, a 1-acre hop yard with a trellis 19 feet high was built. In the first two years, yields were very low. The main reason was premature flowering that limited the vegetative growth. At that time, many plants grew only halfway up the trellis. This happened because the daylength in Florida is not long enough for hops. In general, the critical daylength for hops is 15 to 16 hours. Hops promote vegetative growth when daylength is above this threshold, and plants start flowering when daylength drops below this threshold. The optimal shift from vegetative to reproductive development is key to maximizing hop yields.

    UF/IFAS researchers experienced lots of trial and error. In 2018, LED lights were installed in the hop yard. The daylight extension with LED lights was effective in controlling the timing of flowering. In other words, it can trick hop plants into thinking they are in the Pacific Northwest.

    All trials were reestablished using tissue-cultured seedlings. Researchers have tested more than 20 varieties and various crop management practices, including fertilization, irrigation, plant spacing and pruning. The hop yard is also being monitored to identify pest issues, including diseases, insects and nematodes.

    TRELLIS TRIALS AND HIGH YIELDS

    Research continued in 2019, with another 1-acre hop yard built to test different trellis designs and heights. The straight trellis has only one cable per row, which is for installing both LED lights and twines. By contrast, the V-trellis has three cables per row: the middle cable is used to hang LED lights, and the other two are used to install twines. The most notable difference is that the straight trellis can have only two twines per hill, whereas the V-trellis can have four twines per hill.

    Supplemental lighting is used to extend daylength hours. Photo by Shinsuke Agehara

    In the spring of 2020, researchers started a new trial to evaluate the two trellis designs with three different heights: 12, 15 and 18 feet. A record high yield was achieved. Cascade hops grown on the 18-foot V-trellis produced 1,130 pounds of dry hops per acre, which is more than 60 percent of the commercial average yield of this variety. Alpha acid of these hops, which is an important quality attribute for bitterness of beer, was at the commercial level or even slightly higher.

    It’s important to note that 1,130 pounds per acre is just the first season yield. It normally takes a few years before hop plants can reach the full yield potential, so the yield is expected to go up over time. Furthermore, Florida can produce two crops a year because of the warm climate, whereas other production regions, including the Pacific Northwest, can harvest hops only once a year. Within the next few years, researchers will know if Florida can achieve above-average yields!

    In the meantime, the economics of this new crop need to be investigated. The total material cost for the GCREC hop yard establishment was $15,780 per acre for the straight trellis and $18,687 per acre for the V-trellis. Labor and crop management cost information is now being collected. Budget analysis is expected soon and will determine the breakeven price and yield for each trellis design.

    DEVELOPING A VIABLE INDUSTRY

    In 2019, Florida ranked fourth in the nation for craft beer production, with 329 breweries producing 42.6 million gallons of beer and generating an economic impact of more than $3 billion. The UF/IFAS hops research goal is to develop a viable industry for Florida growers and brewers.

    Florida’s hop industry is just forming. There are several growers producing and selling hops to local craft brewers, and the production is expanding. More than 15 craft breweries in Florida have brewed beer using Florida hops.

    The viability of this new crop in Florida is still unknown. The hope is that research information can support the development of the new industry and help local brewers make more beer with locally grown hops. The latest hops research updates are available at www.facebook.com/GCREC.Hops.

  • Building Better Soil

    A cover crop mix of sorghum and sunn hemp produces positive results for Honeyside Farms.

    By Tiffany Bailey and Ida Vandamme

    It was about 18 months ago when we began planning our first crop to be planted on our newly certified organic field at Honeyside Farms in Parrish, Florida. The field was previously used for pastureland. It was easy to see that we would be starting from a soil structure that is common in our area: very sandy with low amounts of existing organic matter. We quickly learned that building these soils would need to become a priority.

    It can be common for issues to surface during the first few months of converting from perennial pastureland to vegetable production, and that is exactly what we experienced. Our first major problem was due to the microbe populations living in the soil. We were tilling the land for the first time in possibly decades, and we believe that practice turned the existing microbial ecosystem on its head.

    Without the introduction of good bacteria and fungi suited for vegetable farming, our organic crops were especially vulnerable to disease pathogens coming from infected seeds, neighboring farms and even on our equipment and shoes. It was a huge challenge! But, over time, we began to build up the proper microbe population for our farm. Planting cover crops proved to be an important part of building healthy soil.

    COVER CROPS OFFER BIG BENEFITS

    Cover crops are a very helpful tool in aiding and maintaining this transition. Unlike perennial pastureland, cover crops for vegetable farming are annual, covering the ground for a few months at a time (very convenient for your off season when it’s not practical to grow your main crop). Cover crops grow very fast, covering and protecting the soil from erosion.

    Root mass grows down, infiltrating, breaking up compaction, improving structure and excreting exudates that condition the soil and attract good bacteria. Above ground, leaf matter adds literally tons of biomass that contributes to organic matter when broken down and attracts all kinds of beneficial insects and wildlife. There are so many more benefits to cover crops; these are just the main ones.

    COVER CROP OPTIONS

    Honeyside Farms has grown sorghum-sudangrass, sunn hemp, buckwheat and cowpeas for cover crops. As an organic farm, we preferably use organic seed. However, organic cover crop seed is not always widely available. Most certifying agencies will make exceptions when certified organic seed is not available.

    Sunn hemp is probably our favorite cover crop. According to a Sustainable Agriculture Research and Education publication, sunn hemp can produce 5,000 pounds of dry matter per acre and 120 pounds of nitrogen per acre. That’s enough slowly available nitrogen to feed some crops from start to finish without needing to add any extra nitrogen.

    Sorghum is also very beneficial. The sorghum-sundangrass hybrid is more productive in biomass and leaf matter, which is more beneficial as a cover crop than grain sorghum. Sorghum-sudangrass has been recorded to produce up to 18,000 pounds of dry matter per acre. The roots are perfect for scavenging any leached nutrients from the previous crop and putting them within reach of the next crop, thus minimizing pollution and making effective use of nutrition. Sorghum is also known to suppress diseases and nematodes by breaking up their life cycle and producing compounds toxic to them.

    Cowpea is a legume. As a climber, it can be a nice addition to any tall cover crop mix like sunn hemp and sorghum. We have seen that cowpeas and buckwheat can provide significant sources of nectar and food for beneficial insects that we want to attract to the farm. Buckwheat acts as a great short-term cover and easily breaks down. It’s perfect for the 40- to 50-day gap between crops when other covers would take too long.

    COVER CROP MANAGEMENT

    When planting, it’s important to broadcast the proper amount of seed per acre. If the seed is planted too thin, one can miss out on biomass production. But there is no need to waste seed and money planting too thick. Before applying any fertilizer to the cover crops, we take samples and follow what the soil report recommends at planting.

    The best time to knock down the cover crop is when the biomass is optimized, but before the carbon-to-nitrogen ratio gets too high and before seed set to prevent weeds. We allow a few weeks to let the cover crop break down enough so that it is not tying up nitrogen that should be available for our main crop. Sometimes before planting a cover crop, we can tell that this timing will not match when we need the field ready to grow a crop. But we find it better to still plant cover crops and gain some of the benefits rather than let the land sit bare and gain nothing or possibly even lose valuable soil due to erosion. Allow a few weeks to let the cover crop break down enough that it is not tying up nitrogen that should be for your main crop.

    Most challenges come from what is limited by resources, time and practicality. Nothing will be gained if no time is taken to plan for cover crop management. But with proper intention and planning, planting cover crops will provide long-term benefits for many seasons to come.