AgNet DEMO

Author: Robinson

  • UF/IFAS Industrial Hemp Pilot Project: Progress and Plans

    By Lourdes Rodriguez

    Industrial hemp samples at the Everglades Research and Education Center. Photo taken 11-07-19.

    Just past the midpoint of a pilot project to study if industrial hemp grows well in Florida, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers are already looking ahead to see what more they can learn.  

    The UF/IFAS Industrial Hemp Pilot Project team of scientists is engaged in a two-year research project started with hemp plantings in the spring of 2019. A report on the project’s findings will go to the Florida Legislature at the project’s completion but are heading out to growers in the state interested in industrial hemp.  

    “Our call to action is to help growers and investors make an informed choice whether to take a chance on hemp and how to grow it,” said Zachary Brym, assistant professor of agronomy at the UF/IFAS Tropical Research and Education Center (TREC) in Homestead and research lead for the pilot project. “The fact remains that Florida is an entirely new environment for industrial hemp.”

    Among other research objectives, UF/IFAS scientists are working to identify varieties suitable for growing in Florida and develop management practices and cropping systems that are economically sustainable. They’re also identifying risk factors such as insects, disease and the invasive properties of hemp. 

    “The long-term goal of the project is to produce hemp crops in an environmentally conscious and socially responsible way while maximizing both plant health and yield,” said Brym. 

    PRELIMINARY FINDINGS

    As the UF/IFAS Industrial Hemp Pilot Project team begins its second year of studies, researchers are warning growers of potential challenges that can affect the crop’s chances of success.   

    “Be cautious,” said Brym. “There remains a conspicuous lack of consistent science and support for genetics and management practices of hemp for Florida. Our work from 2019 looked at 45 or so varieties across the state. We cannot yet name any variety that did everything a farmer needs to grow a marketable product. We did see some hemp grow well in our trials, so we have something to work with.” 

    According to Brym, some varieties do not match the amount of daylength in the regions tested and flowered too soon. Some showed extremely high variability in growth and productivity. Many exceeded the 0.3 percent total delta-9 tetrahydrocannabinol (THC) limit at harvest.  

    “Each of these preliminary findings point to a risk for farmers,” said Brym. “I am also concerned about the risk to the environment.”  

    Reliable or consistent science-based information on fertilizer and irrigation needs for the plant do not yet exist.  

    “I worry that farmers will apply too much fertilizer or irrigation,” said Brym. “Our early work also begins to confirm the risk of hemp to escape from cultivation through errant seed banks and dispersal.”  

    Brym stressed the preliminary nature of these results and the opportunities to improve the outlook in the second year of the project. Given the need for more information and consistent results, scientists, like Brym, seek support for continued research.  

    “I hope that folks see the value in our preliminary findings. It’s important to report what we see from the science for better or worse,” Brym shared. “There’s a lot more work to be done.” 

    TRIALS AND EXPANSION

    As part of the project, UF/IFAS established variety trials representing various uses (fiber, grain and CBD) from regions of origin throughout North America, Europe and Asia. 

    The trials were planted outdoors at three UF/IFAS research locations including the TREC in South Florida, the Agronomy Forage Research Unit in Hague and the North Florida Research and Education Center in Quincy. The first locations represented the broad range of environments, climates and farming regions of Florida. They provided the ability to assess the genetics, management practices, cropping systems and potential risks of growing in those regions, said Brym. 

    An invasion risk assessment at the Bivens Arm research site, located near UF’s main campus in Gainesville, has been assessing natural conditions and habitats where hemp might establish and spread outside of cultivation. The study looks at the risk of any hemp plants becoming invasive threats to Florida’s landscapes.

    According to Brym, research has expanded with industrial hemp currently being grown at eight permitted UF/IFAS locations. Cultivation now includes greenhouse propagation as well as outdoor planting. Following the initial screening of varieties, additional trials were planted to improve seed emergence, pre-plant seed treatments, herbicide control and soil drainage.  

    What started with a core team of seven faculty members from three departments and the College of Pharmacy has expanded to 20 faculty members from a greater variety of disciplines. 

    Researchers from the expanded team looked into the basic physiology of hemp in a controlled environment and monitored for pests and diseases on hemp outdoor trials. Their involvement was critical when two propagation greenhouses went under quarantine for pests that appeared on transplants from outside of the state after initial delivery inspections.  

    “We can thank the continued industry support and investments that helped us meet our research milestones. Our research efforts to date have made great strides in making information available to this emerging industry,” said Brym. “We’re geared up to complete the pilot project in 2020 and look forward to continued engagement with the industry.” 

    To stay up to date on new developments, visit the UF/IFAS Industrial Hemp Pilot Project website.  

  • Fusarium Wilt: A Quick Review

    Integrated techniques are needed for fusarium wilt management.

    By Nicholas S. Dufault

    It has been more than 120 years since an unknown watermelon wilt disease was observed to cause heavy losses in the southern United States. The re-emergence of this disease, identified as fusarium wilt (FW) caused by the fungus Fusarium oxysporum f. sp. niveum (Fon), has led to a need for alternative control practices.

    MANAGEMENT STRATEGIES

    Numerous FW disease management strategies have been developed such as fumigation, long-term (>7 years) crop rotation, delayed planting, grafting and host resistance. This article will briefly discuss the pros and cons of current management techniques and explain how improved diagnostics with a better understanding of risk is important for future management of FW.

    The techniques listed above can all be effective at managing FW. However, inconsistent results related to fumigation as well as delayed planting in Florida have led to a need to further investigate when and how to implement these management options. Grafting and cultivar resistance both provide effective control of Fon, but cost or mixed pathogen populations can impact their usefulness, respectively.

    For example, the deployment of a resistant cultivar, even if it is not specific to all the races in the field, can result in less wilting than cultivars without resistance. The effectiveness of this technique is increased when the predominant pathogen present is the same race as the resistance trait. Unfortunately, there are times when the Fon population present in the field is not affected by resistance, which leads to significant wilting and losses.

    NEW TOOLS AND MORE KNOWLEDGE NEEDED

    Thus, deployment of new resistance sources is needed in combination with more accurate pathogen diagnosis techniques. Integrating these techniques, as well as others, will likely provide more consistent results for disease management. Finding the optimum integrated technique will require more information about the pathogen and disease risk.

    To improve risk assessment for FW, a bioassay is being assessed that can help detect the pathogen in the field after a long rotation. In addition, a climate/risk index tool is being developed to determine FW risk. These tools can provide further insights into the risk associated with FW but should only be considered as decision support aides and not prediction tools. The effectiveness of these tools will be improved by better documenting the Fon genotype present within a given field.

    Research currently being conducted across the Southeast is focused on expanding the understanding of the pathogen’s genetics. This genetic information can also be used to improve the understanding of the FON races and maybe even provide insights into what makes the pathogen virulent. As further information is gained about the pathogen’s genetics, it can be combined with breeding programs to focus on these virulence traits and used to improve disease diagnostic methods in the field and on the seed.

    Substantial progress has been made on understanding FW management. Unfortunately, no single method has proven to be completely effective or economically feasible for disease control. Improved knowledge about the pathogen’s genetics will be critical to implementing proper integrated management techniques as well as accurately assessing disease risk related to field history, climate and diagnostics.

  • Tips for Two Troublesome Watermelon Diseases

    Phytophthora symptoms on watermelon fruit
    1: Photo by David B. Langston, University of Georgia, Bugwood.org
    2: Photo by Jason Brock, University of Georgia, Bugwood.org

    By Bhabesh Dutta

    Phytophthora fruit rot has been a concern for watermelon growers not only in Georgia but also in other states that grow watermelon. No single measure has been shown to suppress the disease consistently and effectively, especially when environmental conditions are favorable for disease development.

    Compared to other watermelon diseases, this disease is difficult to manage and strictly requires an integrated management program. Unlike on other cucurbit hosts (squash and cucumber, for example), phytophthora symptoms often appear on fruit and not on foliage. However, research indicates that all growth stages and plant parts are susceptible to infection.

    In watermelon, fruit symptoms are quite common. Some of the common symptoms that can be observed on fruits are irregular to round, water-soaked lesions that become brown. As the disease progresses, concentric rings of pathogen sporulation may appear within a lesion.

    Lesions can appear on the upper and/or lower surfaces (contact with the soil) of fruit. As the pathogen is soilborne, symptoms on the lower surface are quite common. Symptoms on the upper surface are presumed to be related to the dispersal/spread of the pathogen from contaminated soil. Under favorable conditions, complete rotting of fruit is common.

    Phytophthora capsici can survive in soil or in host plant debris by means of thick-walled spores (oospores). Researchers have associated irrigation from contaminated pond water with P. capsici outbreaks in watermelon and other vegetable crops in Georgia.

    The pathogen has two mating types (A1 and A2). Both mating types are necessary for oospore production. Presence of both mating types in vegetable fields is not uncommon in Georgia, which makes management more difficult. Spread of the pathogen is aided by zoospores, which are asexual spores that can swim in free moisture in the soil or on the plant surface and can infect the host. Zoospores are formed in specialized saclike structures called “sporangia” that can also spread by wind-blown rain and be carried through water.

    Resistant watermelon varieties are not available. As a cultural control, it is recommended not to use retention pond water for irrigating watermelon crops. It is also advised to have good drainage in watermelon fields, which is sometimes difficult to achieve.

    A preventive fungicide program is the key to get ahead with this disease. A fungicide program comprised of Presidio, Orondis Gold, Revus and Elumin may help.

    Downy mildew symptoms on watermelon leaves
    Photos by Jason Brock, University of Georgia, Bugwood.org

    Downy mildew has been a sporadic issue in watermelon as its incidence varies from year to year in Georgia. Unlike classical angular leaf spot symptoms that are observed in cucumber, symptoms on watermelon can be difficult to diagnose. Symptoms may start as irregular yellowish to brown spots that gradually become necrotic and often appear on upper surfaces of leaves. Lesions are often visible near the crown. As the disease progresses, necrotic lesions may appear on both sides of the leaf.

    This disease can spread rapidly, aided by high humidity and wind-driven rain. Severe defoliation can be seen if timely management practices are not employed. Fruit rot due to sun scalding soon follows.

    Resistant varieties are not commercially available. Crop rotation is impractical as the inoculum doesn’t survive locally in Georgia and arrives from Florida via wind current or any kind of weather events.

    A preventative fungicide program is the key to get ahead with this disease. A fungicide program comprised of Ranman, Orondis Ultra, Revus and Elumin may help. Chlorothalonil (Bravo) can be used as a protectant until fruit set.

  • Wildflowers Impact Watermelon Pollinators

    1) A bumblebee and sweat bee forage on the same flower, Cosmos sulphureus.
    2)Sweat bees (Lasioglossum spp.) are so small they often go unnoticed. Sixteen species of these bees were collected visiting watermelon.
    3) The Southern plains bumblebee (Bombus fraternus) is a frequent watermelon and wildflower pollinator on farms in South Carolina.

    By Mimi Jenkins

    A resilient and stable pollinator community includes a diverse suite of pollinators with a range of nesting habits, foraging behaviors and activity periods. These different behaviors and traits complement each other and can buffer against any year-to-year fluctuations or environmental changes that affect species differently.

    BEYOND HONEY BEES

    In many pollinator-dependent crop systems, honey bee colonies are brought onto the farm to provide the pollination services necessary to produce the crop. In the case of watermelon, a monoecious plant with separate male and female flowers that make it entirely dependent on pollinators to set fruit, using honey bee hives to pollinate the crop is widely recommended for growers to achieve high yields. While honey bees are an important agricultural pollinator, especially for industrial scale farms, considering alternative pollination sources that already exist in the natural environment helps buffer against ongoing honey bee losses and the rising cost of renting honey bee hives.

    Wild native bee communities rely much more on the natural habitat of an area than honey bees because of their different nesting habits and because they are not actively managed by humans. Wild bees require habitat that provides food (flowers) and shelter (nesting materials and proper soil/environmental conditions). Other pollinating insects, such as flies and butterflies, share the need for floral resources with bees but many do not have a nest, and others require certain plant hosts or prey in their larval stage.

    The flowering period of the wildflowers in this South Carolina strip began in May before watermelon bloom and lasted long after watermelon was done flowering, into August.

    Implementing on-farm enhancements such as wildflower strips is one way to increase the availability and diversity of food resources for pollinators beyond the crop bloom period. Traits that should be considered for wildflowers in farm fields include: drought-tolerance, native to eco-region, fast germination rates, hardiness, difference in flowering period, length of flowering period and attractiveness to a variety of pollinating insects.

    RESEARCH RESULTS

    In a study I conducted from 2016 to 2018, the number of visits to watermelon was significantly higher for one group of pollinators (sweat bees in the genus Lasioglossum) when wildflowers were in a watermelon field compared to fields without wildflowers. These small, metallic grey-green bees nest underground and do not forage more than a few hundred meters from their nest.

    In addition, the overall biodiversity of the pollinator community was higher in watermelon fields with wildflowers strips, with nearly twice the number of pollinator species collected on watermelon fields with wildflowers compared to control fields. The mean number of watermelon pollinating species per field was 15 species, and the mean number of total pollinators (including wildflower pollinators) per field was 24 species.

    More than half (64 percent) of the watermelon pollinator species collected were also collected visiting one or more of five wildflower species in the study. This demonstrates that social colonies of bees, solitary bees and other insects like syrphid flies and butterflies utilize the multiple floral species as resources on the watermelon field in addition to the crop flowers when they are available. In fields with wildflowers, we also observed and collected a wide range of pollinators and insects that do not visit watermelon flowers but visited the wildflower species, such as several swallowtail butterfly species, cleptoparasitic bees and sunflower bees.

    In conclusion, when wildflowers and weedy flowers are available on the farm landscape, a more diverse community of beneficial insects is supported. This community included declining species like Monarch butterflies, the American bumblebee and the Southern plains bumblebee as well as parasitic and predatory flies and wasps that can control crop pests.

  • Asian Vegetable Crop Interest Increasing in Florida

    By Mary Dixon, Yanlin Wang and Guodong Liu

    At the 2019 Florida Ag Expo, visitors gathered at the Gulf Coast Research and Education Center (GCREC) for a trade show and field tour. Students and faculty from the University of Florida (UF) set up an Asian vegetable display that was visited by approximately 75 growers, educators, students and Extensions agents. Visitors conversed with students, read a flyer, took an identification quiz and watched a cooking video featuring Asian vegetables. They also had the opportunity to speak with UF associate professor Guodong Liu, who has dedicated much of his time toward exploring how to grow Asian vegetables.

    Yanlin Wang, a UF graduate student, presented research on nutrition of Asian vegetables. She determined optimal fertilization of conventional luffa and long bean to be 150 and 200 pounds per acre of ammonium nitrate, respectively. Luffa was on display as well as nine other vegetables.

    Luffa grows well in Florida because of the heat and moisture (Herklot, 1972; Purseglove, 1968). The two typically grown species are smooth (Luffa aegyptiaca) and ridged (Luffa acutangular). Mature fruit can be made into a fibrous sponge, and immature fruit are rich in minerals (phosphorus and potassium) and vitamins A and C (U.S. Department of Agriculture-Agricultural Research Service). The young leaves, flowers and buds can be eaten (Xie et al., 2016). Luffa has been used medicinally to treat diabetes and reduce risk of heart disease (Schilling et al., 1981).

    Tong hao is an annual that grows highly branched foliage. It is slightly aromatic and has high quantities of beta carotene and antioxidants. It can be used culinarily, ornamentally or as green manure.

    Nappa cabbage is a mild elongated Chinese cabbage also known as wong bok (meaning yellow white) because of its typical yellow heart. It is an incredibly healthy vegetable that is an excellent source of folic acid, vitamins (A and B) and calcium (Mendes de Lira et al., 2015).

    Daikon radish is a mild Japanese radish with diuretic properties. Daikon radish forms a large taproot and dense foliage which may help reduce weed pressure. It decomposes quickly, releases nutrients and opens channels in the soil from decomposing roots, indicating cover crop potential (Gruver et al., 2016; Weil et al., 2009).

    Yu choy is a cool-season leafy annual with slender, pale green stems. It is typically harvested after one month, but harvest time may vary. Yu choy has high concentrations of antioxidants and mineral nutrients (Kamarudin, 2012). The leaves, stems and flowers are all edible and taste peppery and sweet.

    Shanghai bok choy has a light-green stem with smooth, spoon-shaped leaves. This crop can be grown in most parts of Florida year-round (Stephens, 1994). Harvest typically occurs after 30 to 45 days, and bitterness may develop if left in the soil too long (Tay and Toxopeus, 2016).

    Bitter melon is a vine from south Asia that has spread through the tropics and subtropics (Hossain et al., 2006). It grows rapidly, so trellis-support is recommended. Immature fruit tastes pleasantly bitter and is an excellent source of vitamins (A, B and C) and minerals (calcium, phosphorus, potassium and iron). Chinese bitter melon tends to be smoother and less bitter than Indian bitter melon. Bitter melon also has medicinal benefits like lowering blood sugar (Zhang et al., 2018).

    Kabocha is a winter squash that grows best in well-drained soil with organic matter (Liu et al., 2017; Purdue Extension, 2014). The yellow-orange flesh is sweet, starchy and firmer than common pumpkin. The seeds can be roasted and taste like pumpkin seeds.

    Long squash is an herbaceous vine that needs trellis support. Long squash is a good source of vitamin C and potassium and has anti-inflammatory and cardioprotective effects. While not edible, the mature fruit can be used as containers, musical instruments or fishing floats.

    Chinese eggplant is a perennial typically grown as an annual. It is long and has thin skin and few seeds. Chinese eggplant has been used medicinally for its antioxidant properties and for symptom reduction of toothaches, sores and intestinal disorders (Moore, 2007).

    Asian vegetables grow well in Florida and have high market potential. John Sykes, a potato farmer with more than 1,000 acres of land, now grows Asian vegetables. He sees a market for them throughout the United States and in Canada.

    Asian vegetable cultivation may be a novel and profitable experience. To learn more, search the UF Institute of Food and Agricultural Sciences Electronic Data Information Source website (https://edis.ifas.ufl.edu/) or visit https://hos.ifas.ufl.edu/people/on-campus-faculty/guodong-david-liu/how-to-grow-asian-vegetables/.