AgNet DEMO

Author: Robinson

  • Supplemental Fumigation Strategies for Tomato Production

    © Matthew Dicker / shutterstock.com

    By G.E. Vallad, J. Desaeger, J. Noling and N. Boyd

    Vegetable and strawberry growers have long relied on soil fumigants to contend with various soilborne pathogen and pest complexes, as part of an integrated management strategy that includes crop resistance, cultural control and pesticides. However, with the loss of methyl bromide (MBr), many growers have struggled to maintain consistent soilborne pathogen and pest control with the available fumigants.

    Much of this relates to the inability of available fumigants to disperse throughout the soil in the same manner as MBr. This is due to the physical differences in volatility, as revealed by comparing the vapor pressure and boiling points (see Table 1) of currently available fumigants to MBr and water. Volatility is the tendency of any substance to convert to a gas at a given temperature and is directly related to the substance’s specific vapor pressure, which is inversely related to boiling point.

    Figure 1. The Yetter Avenger Coulter system has a pair of coulters straddling the raised bed. Final application depth is greater than 8 inches below the soil.

    By comparing vapor pressure and boiling point values of fumigants to water, it is easier to understand why the current fumigants are referred to as volatile liquids. Vapor pressure values for Pic and 1,3-D are on average 70-fold less than MBr at 20° C (68° F), and the ITC generators are even less volatile with physical characteristics more similar to water. MBr, as a true gas, would rapidly volatilize from a liquid once applied to the soil and quickly fill available airspace within the soil profile. In comparison, all the current alternatives remain liquid following application and then slowly volatilize. These physical characteristics limit fumigant movement within the soil of the prepared, raised bed.

    Figure 2. Roots are emerging below the plastic tuck from the side of the bed.

    Unfortunately, threats from soilborne pathogens and pests are not always limited to the immediate raised bed. For example, research previously demonstrated that supplemental applications of chloropicrin along bed edges below the tuck (Figure 1) protected tomato roots emerging from the fumigated bed into non-fumigated soils (Figure 2), which subsequently reduced the incidence of fusarium wilt (Figure 3). Similarly, research demonstrated that deep-shank soil applications of 1,3-dichloropropene (Telone) (Figure 4) were necessary to manage nematode populations deeper in the soil, below raised beds, that were beyond standard in-bed fumigant applications (Figure 5).

    Figure 3. A field trial demonstrates the supplemental application of Pic 100 to bed edges compared to the grower standard of Pic-Clor 60 alone.

    FIELD TRIALS
    Many operations have problematic fields with a complex of soilborne pests and pathogens. Large replicated field trials were recently conducted to address such situations, combining both supplemental approaches in tomato fields affected by root-knot nematodes and fusarium wilt. Combinations of deep-shank Telone II, with in-bed fumigation, supplemental chloropicrin and plastic mulch [virtually impermeable film (VIF) vs. totally impermeable film (TIF)] were evaluated.

    Figure 4. A broadcast, deep-shank application of Telone II (inset shows applicator). The tractor at top is making a 16 to 18-inch application at 12 gallons per acre, followed by a disk to disrupt chisel traces (center pass) and then packed with a roller to seal the fumigant (bottom pass).

    Two fields received deep-shank applications of Telone II (12 gallons per acre) in 600-foot by 50-foot strips alternated with 50-foot non-fumigated strips across the entire field. A month later, raised beds prepared over the Telone II strips received in-bed applications of either Pic-Clor 60 (300 pounds per acre), Pic-Clor 80 (225 pounds per acre) and Pic 100 (180 pounds per acre) with supplemental application of Pic 100 along the bed edge (150 pounds per acre).

    Raised beds prepared over the non-Telone II strips received Pic-Clor 60 (300 pounds per acre) either with or without the supplemental Pic 100 along the bed edge as additional controls. Each of the described combinations were covered with both TIF and VIF plastic mulch (for a total of 10 treatments) and then planted accordingly. Each treatment plot consisted of three beds (approximately ¼ acre) and was replicated five times in each field.

    RESEARCH RESULTS
    Two weeks after deep-shank applications of Telone II, deep soil cores pulled across fumigated and non-fumigated portions of the field found total nematode levels (including parasitic Meloidogyne species) were reduced by 82 percent, from an average of 8.3 nematodes per 100 cubic centimeters of soil to 1.1 nematodes. The reduced nematode counts were further reflected at the end of the season with a 97 percent reduction in root-knot galling between deep-shank Telone II and non-deep-shank fumigated plots.

    Figure 5. A demonstration of deep-shank applied Telone II on root-knot nematodes in cucumber. Telone was applied perpendicular to raised-bed preparation. The image shows a strip where the deep-shank applicator was turned off.

    Supplemental Pic applications reduced average root gall ratings 24 percent and reduced average fusarium wilt incidence by 47 percent. Unexpectedly, deep-shank Telone II applications had the greatest statistical effect on fusarium wilt, reducing disease incidence by 66 percent, from 19.4 to 7.5 percent average incidence across all treatments. In-bed fumigants also had a significant but minor effect on average root gall ratings and fusarium wilt, with in-bed Pic-Clor 60 and Pic-Clor 80 performing better than Pic 100.

    Statistically, mulch had no effect on nematode gall ratings, fusarium wilt or yields. In-bed fumigation had numerical but no statistical effect on tomato yields. A replicated lab study further demonstrated the fungicidal activity of 1,3 dichloropropene (Telone II) against Fusarium oxysporum f. sp. lycopersici. Several other studies have reported similar findings for 1,3 dichloropropene against soilborne pathogens and for chloropicrin against nematodes.   

    CONCLUSION
    These findings further support the notion of developing supplemental fumigation strategies that target soilborne pests and pathogens at their source. These supplementary approaches are meant to be prescriptive in nature, based on the specific soilborne pest or pathogen problems observed in fields.

    Current and future research will address the frequency of supplemental fumigation and the use of other fumigants, as well as reducing in-bed application rates to help offset the cost of supplemental fumigation. Improvements in available post-plant fungicides and nematicides may also change fumigation strategies, as well as the availability of crop varieties with improved tolerance to soilborne pathogens and pests. Parties interested in participating in such studies are welcome to contact Gary Vallad at gvallad@ufl.edu or 813-419-6577.

  • Bioengineered Sentinel Plants Could Help Protect Future Crops

    Illustration by Snow Conrad

    By Jenelle Patterson

    As a plant molecular biologist, I often hear tales of gardening mishaps or plant-related tidbits from my friends and family.

    A few years ago, a friend excitedly relayed her experience at a Niagara wine tour, where the tour guide explained that they grow rose bushes at the end of each row not only for aesthetics, but as early warning systems for pests and diseases (such as powdery mildew). This piqued my curiosity, and I discovered that using plants as biosensors or sentinels is not a modern concept. Roses have been used this way for centuries.

    However, the use of roses as sentinels has disadvantages:

    1) Some pests or pathogens that target grapes do not affect roses.

    2) By the time a rose shows signs of a fungal infection, it may be too late to protect the grapes.

    Most modern vineyards employ more sophisticated integrated pest management strategies (e.g., forecasting disease outlooks using weather reports and tracking confirmed cases). But, this canary-in-a-coal-mine approach of using plants as warning systems still may prove useful, especially where other types of testing are unavailable or costly.

    ADDRESSING SENSITIVITY AND SPECIFICITY

    A diverse array of agricultural and human health hazards (pathogens, heavy metals, herbicide residues, radioactivity, even explosives, to name a few) could conceivably be detected using sentinel plants. But we first need to address the reasons why roses fall short: sensitivity and specificity.

    The first attempts to bioengineer sentinel plants began in the late 80s with the discovery and development of reporter genes (think of them as biological red flags). By the 90s, engineered plants were designed that could detect genotoxins (chemicals or UV-C light that cause DNA mutations). Prolonged exposure to genotoxins causes mutations in the plants, which were measured by staining the plant tissue with a chemical that turns cells blue if the reporter gene is mutated.

    These plants could detect heavy metals, herbicides and radioactivity just as effectively as conventional methods that use animals or chemical analysis. And these sentinel plants were cheaper, required less maintenance and avoided the ethical concerns of using animals. Despite being a big step in the right direction, prototypes had the same issues as their natural rose counterparts: The tests took weeks to months of exposure (sensitivity) and could not be used to identify the genotoxin, only to indicate that one was present (specificity).

    Bioengineering has made huge progress in the past decades as scientists develop new technologies and a better understanding of how plants naturally detect and react to changes in their environment. Plant researchers are beginning to rethink biology in terms of computer programming, adopting concepts like modular system design and logic gates.

    Simply put, biological components are being treated like modular parts used to build an input/output system. Plants and all living organisms use this kind of system already. A signal is detected (e.g., getting chewed on by a bug), that information is relayed in a game of telephone by enzymes and signal molecules, generally ending in the nucleus (the control center of the cell), which flips a genetic switch to bring about some response. The power of bioengineering is the ability to design a tunable system, one that is sensitive to a specific input.

    In 2011, researchers tested this principle by building a TNT-detector plant. They integrated genetic parts from bacteria into a plant’s natural stress-response pathway. Their creation could sniff out and signal the presence of soil- or airborne TNT molecules (input) by causing leaf de-greening (output), and at equivalent levels to bomb-sniffing dogs. This landmark study was just the beginning. It demonstrated the potential for bioengineered sentinel plants to address the sensitivity and specificity limitations of their natural predecessors.

    RESEARCH ADVANCEMENTS

    Researchers have since been identifying and redesigning biological parts to build complex logic gates. Early bioengineered systems were only capable of binary on/off states. Building more complex systems by adding modular components that work together gives the plant the ability to make more nuanced ‘decisions’ (like computer logic gates: react to this and/or this, but not to that). This can reduce false positives and allow for more sensitive detection. Different reporter outputs can also be used to reduce testing times and avoid destroying the sentinel plant, such as engineering plants to produce fluorescent proteins in their leaves, which is easily visible under a UV lamp.

    Researchers still have more work to do to make sentinel plants reliable enough for routine use in agriculture. But it’s not hard to foresee a future where genetically trained roses are a critical part of modern integrated pest management, and not just a nice story to tell guests on a wine tour.

  • Top 5 Lessons Learned From a Newly Certified Organic Grower

    Tiffany Bailey, owner of Honeyside Farms, with her brother and business partner, Paul Bispham Jr.

    By Tiffany Bailey

    At Honeyside Farms, we have been growing produce using organic practices for over 10 years. When we needed to move farm locations, we found a piece of farmland that could become certified organic. So, we decided to go for it. These are the top lessons we learned in our first year as a fully certified organic farm.

    1: RECORDS ARE YOUR FRIEND

    Before deciding to become certified organic, we spoke with many growers about the benefits and challenges of becoming certified. One of the constant negatives we heard about was intense recordkeeping. The recordkeeping has proven to be intense, but the information we have collected has been extremely valuable. We quickly discovered that we needed to plan recordkeeping into every day.

    We use a series of Excel spreadsheets on a computer to keep track of all our records. At the end of every day, our farm manager cools off in the air conditioning while updating all the spreadsheets with information from that day. This usually takes about 30 minutes. When the season is wrapping up, it has been well worth the time to sit down and analyze how the information we collected can be used to make future decisions.

    2: YOU CAN’T GROW EVERYTHING

    While it may seem obvious that different crops have different costs, it is important to evaluate the costs involved with everything from seeds to post-harvest and handling. Especially on a small scale, not all crops can bring in enough revenue to justify growing and handling them.

    This can be hard, especially when you have an item that is a customer favorite. But it is important to understand all the different types of costs so you can grow what makes sense financially. If you don’t make the money you need, you won’t be able to sell anything to your customers.

    3: NEW GROUND BRINGS NEW CHALLENGES

    If you are going to grow something on a new piece of ground, expect to deal with some new challenges. Sometimes there is just no way of knowing how something will grow until you have your first crop there. Consider growing a lower risk type of crop on the first go-around. This will give you an opportunity to assess things like drainage, nutrient retention and soil insects.

    On one of our new blocks, we discovered a heavy population of mole crickets that fed on our seedlings. It was an expensive discovery, but we did gain knowledge on how to approach new ground.

    4: CAREFULLY SOURCE YOUR LIQUID FERTILIZER

    These days, there are so many Organic Materials Review Institute products to choose from. Many liquid fertilizers have good numbers on the label but can come with some challenges related to clogging filters and drip tape. Make sure you know another grower who has used the product successfully before you commit to using it.

    You may not get everything you need in one liquid blend. You may have to apply certain nutrients through foliar applications or from a dry mix.

    5: THE WORK IS NEVER ALL DONE

    Organic farming is more work — period. You can’t just spray something and have 21 days of control. So, the field is always needing some sort of attention. And let’s not forget about the office work and recordkeeping that come along with complying with organic standards.

    It is important to make an actual list of your priorities. Manage your time well and try to create routines out of repetitive tasks so you can be as productive as possible. Make sure you are taking time to do important things instead of only doing what is urgent. Sometimes, you have to allow some little fires to burn, and that’s OK.

  • Fumigants for Nematode Management in Vegetables

    Bell pepper roots (left) show severe galling caused by the southern root-knot nematode compared with healthy roots (right) treated with Pic-Clor 60.

    By Abolfazl Hajihassani and Chinaza Nnamdi

    The majority of vegetable production in Georgia is located in multiple counties in the southern region of the state. Vegetables are grown year-round on both raised beds covered with polyethylene plastic mulch and on bare ground.

    Using a comprehensive survey conducted in 2018, we have documented that root-knot nematodes, Meloidogyne spp., are the No. 1 nematode pest in vegetable crops in Georgia, infecting 67 percent of the fields surveyed. Therefore, proper management practices need to be developed or optimized for successful control.

    CONTROL OPTIONS

    Chemical control is currently the best option for managing nematodes in vegetable-producing systems. Optimizing chemical control methods is a must for vegetable growers in the Southeast. Growers often fumigate the soil prior to planting the first crop in the spring or in the fall, but the issue with root-knot nematodes is particularly important in the second, third or fourth crop grown on the same plastic mulch. Reusing mulch favors nematode buildup in coarse-textured soils.

    In Georgia, 1,3-dichloropropene (Telone II), chloropicrin, mixtures of 1,3-dichloropropene and chloropicrin (e.g. Pic-Clor 60), metam sodium (Vapam) and dimethyl disulfide (Paladin) have been the common fumigants for the control of soilborne pathogens, weeds and nematodes in vegetable-production systems.

    In a field study conducted at the University of Georgia Tifton campus in 2019, we evaluated the effects of different soil fumigants on the southern root-knot nematode and yield of bell pepper. Treatments included Telone II (125 pounds per acre), Dominus (250 pounds per acre), Pic-Clor 60 (175 pounds per acre), Paladin (167 pounds per acre) and an M. incognita-resistant pepper cultivar (Carolina Wonder).

    RESEARCH RESULTS

    Results showed that all soil fumigants and the resistant cultivar reduced root galling compared to the untreated check at harvest. Pic-Clor 60 had numerically better control of root galling compared to the other fumigants. At the end of the season, second-stage juveniles of the nematode in the soil were only lower than the untreated check in the resistant pepper treatment. Among the fumigant treatments, Paladin had numerically lower nematode numbers in comparison with the other fumigants. We also found that Pic-Clor 60 and the resistant cultivar had the highest and lowest pepper fruit yield, respectively.

    Based on our data, treatments with Dominus and the resistant variety had the highest weed density. Plots treated with Pic-Clor 60 had the lowest weed density. There was no difference in weed density among Paladin, Telone II and the untreated check. The weed population in the Dominus treatment was higher than the check plot. Soil fumigation with Pic-Clor 60 reduced southern blight disease, caused by the fungus Athelia rolfsii, as compared to other treatments.

    Paladin, though effective in suppressing nematode juveniles in the soil, was withdrawn from the market in 2019, further restricting the already limited number of tools for managing nematodes. Pic-Clor 60 is likely an ideal fumigantfor control of root-knot nematodes and other soilborne pathogens in multi-cropping systems of vegetables. However, root-knot nematode population densities in plots treated with Pic-Clor 60 were increased by the end of the growing season. This may suggest that combined use of fumigants and post-plant nematicides through drip irrigation could provide enough root protection against high densities of root-knot nematodes in the first and subsequent crops grown on the same plastic mulch.

    In collaboration with county Extension agents, two on-farm trials are currently being conducted in Brooks and Lowndes counties in Georgia. The objective is to examine whether the combined application of both fumigant and non-fumigant nematicides in the first crop can result in a more effective control of root-knot nematodes and higher crop yield, compared to the use of only fumigants in the first crop and only non-fumigant nematicides in the second crop grown on the same plastic mulch.

  • Hemp growers: Be on the Lookout for Nematodes

    Figure 1. Stunted ‘starving’ strawberry plants (foreground) caused by sting nematodes in Florida.

    By Johan Desaeger

    Florida’s subtropical climate offers unique opportunities to grow crops outside of the typical growing season of other states. Such is the case for strawberries and many vegetables. There are high expectations that hemp could be another such crop, although nematodes may have something to say about that.

    Plant-parasitic nematodes, such as root-knot and sting nematodes, can cause severe damage to many of Florida’s crops, especially in sandy soils, which comprise much of the state (Figure 1). Nematodes are microscopic roundworms that live in the soil and are one of the least-known and most difficult-to-manage pests that growers can face. Because of nematodes’ small size, belowground nature and lack of easily recognizable symptoms, nematode damage is often not recognized as such. Symptoms typically occur randomly in a field and are easily confused with other pests and diseases, nutritional deficiencies, plugged drip tapes or too much or too little water.

    Figure 2. Swollen and galled roots caused by root-knot nematodes on tomato (left) and hemp (right).

    The most important nematodes in Florida are root-knot nematodes. They can cause damage to a wide variety of crops and are extremely widespread throughout the state (Figure 2).

    HEMP HAS SOME NEMATODE TOLERANCE

    With the considerable interest that hemp is gaining in Florida, the Gulf Coast Research and Education Center (GCREC) nematology lab started to investigate how root-knot and other nematodes may affect this new crop. The hemp-nematode research is the focus of Jackie Coburn, a master’s student in the nematology lab.

    Coburn screened several hemp cultivars in the greenhouse at the GCREC, including fiber, seed and CBD (cannabidiol) hemp types, originating from Europe, China and the United States. Initial data show that hemp is a good host for root-knot nematodes (Figure 2). However, the crop appears to be relatively tolerant, meaning the nematodes can feed and reproduce, but do not seem to negatively affect hemp growth.

    Figure 3. Hemp plots at the Gulf Coast Research and Education Center have strings with LED lights and hops in the background.

    Certain CBD varieties showed less nematode root damage than others, which will be useful for future breeding efforts. Currently, Coburn is screening hemp varieties for sting nematode, another important nematode in Florida, especially in strawberry fields (Figure 1).

    In addition to the greenhouse studies, hemp research was also initiated in the field at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) farm in Balm. Here, hemp cultivars are planted throughout the year. In addition to nematode sampling, plants are being monitored for other pests and diseases.

    HEMP-HOPS INTERCROP

    An interesting feature in the field trials here is that hemp is grown with and without adding supplemental light, a practice that has worked well for hops in Florida (Figure 3 and Figure 4). It quickly became clear that adding supplemental light during the vegetative state makes a huge difference when growing hemp. In field trials, hemp was intercropped with hops, and both crops received the same light and fertilizer regimen.

    Figure 4. Hemp (left) and hops (right) at night at the Gulf Coast Research and Education Center.

    Hops and hemp belong to the same plant family, and in addition to both being daylength-sensitive plants, they also share many of the same flavor and aroma compounds. The field trials at the GCREC showed that with supplemental light, a hops-hemp intercrop can be an attractive option, as both crops will similarly benefit, allowing for two hop harvests per year and two to three hemp harvests per year.

    MORE RESEARCH RESULTS TO COME

    With increasing interest in hemp as an alternative crop, we will continue to provide updates on the hemp research at the GCREC. Future focus will be on CBD varieties and how to integrate hemp in the high-value cropping systems (vegetables and strawberries) in our area.

    Finally, in order to help researchers better understand the real importance of nematodes in commercial hemp fields, we invite any hemp grower in Florida to contact us if they notice abnormal plants in their field, or simply wish to have their fields analyzed for nematodes.

    This story was from the August edition of VSCNews Magazine. To subscribe, see http://vscnews.com/subscribe/.

  • Fungicide Resistance in Georgia Strawberry Fields

    Figure 1. Anthracnose fruit rot of strawberry © Catherine Eckert / shutterstock.com

    By Phil Brannen, Md Emran Ali, Jeff Cook, Sumyya Waliullah and Owen Hudson

    Anthracnose fruit rot disease, caused by fungal Colletotrichum species, is one of the most significant disease problems of commercial strawberry production in the Southeast.

    Dark, sunken lesions on fruit are the main disease symptoms (Figure 1). Hot, humid weather and significant rainfall make Colletotrichum-induced fruit rot a widespread problem in strawberry production.

    For disease control, growers mainly rely on preventive fungicide applications from flower bud emergence to harvest. The most used single-site fungicides are quinone outside inhibitors (QoIs). The QoI active ingredients azoxystrobin (e.g., Abound) and pyraclostrobin (e.g., Pristine) are often utilized to manage anthracnose fruit rot. If appropriate resistance-management strategies are not implemented, QoIs are at increased risk of resistance development and subsequent control failure.

    The QoIs have been marketed since 1996, and resistance development is expected with long-term use, but limited surveys and in vitro efficacy tests conducted in 2004 and 2008 did not confirm QoI resistance in Georgia. However, more recently, producers have complained of control failure when using QoI fungicides, and resistance has been confirmed.

    RESISTANCE CONFIRMATION

    In 2019, county agents submitted numerous samples to the Plant Molecular Diagnostic Lab in Tifton, GA. Md Emran Ali, the lab director, collected 108 strawberry fruits with visible rot symptoms to test for fungicide resistance. These samples were from seven different strawberry farms scattered throughout Georgia. The farms had received multiple applications of QoI fungicides during the 2019 growing season, as well as in previous seasons.

    Ali identified all isolates as Colletotrichum acutatum. For further confirmation of QoI resistance, he tested all 108 isolates for the presence of the G143A mutation using the PCR-Restriction Fragment Length Polymorphism assay. His results showed the presence of the G143A mutation in all QoI-resistant C. acutatum isolates, 87 percent of isolates with moderate resistance, but none with reduced sensitivity or sensitive isolates (Table 1). These findings suggest that there is a high risk that resistance has developed in C. acutatum populations wherever QoIs have been utilized over time for control of anthracnose fruit rot in Georgia – and likely elsewhere.

    GROWER RECOMMENDATIONS

    For effective control of this disease, growers need to focus on using multi-site fungicides, such as Captan products, and alternation with classes other than QoIs. The Southeast Regional Strawberry Integrated Pest Management Guide for Plasticulture Production (www.smallfruits.org), edited by Rebecca Melanson of Mississippi State University, provides excellent information on fungicide selection under various conditions of resistance to anthracnose and/or botrytis fruit rots. 

    Moving forward, growers should have their anthracnose populations tested for QoI resistance. Use of QoIs may be limited in future management strategies as a result of widespread resistance development. The Plant Molecular Diagnostic Laboratory, a lab service of the University of Georgia Department of Plant Pathology, is now providing fungicide resistance testing support for several plant pathogens like anthracnose of strawberry. The clinic can accept symptomatic fruit samples (generally 10 per site) to test for resistance.

    In 2019, funds were provided by the Southern Region Small Fruit Consortium for resistance testing of both anthracnose and botrytis — free of charge to producers from member states until the funds ran out. Check with your local county agent on the status of resistance testing funds. If funds are not available, you are still encouraged to have both anthracnose and/or botrytis profiled for your location. The tests currently available, their pricing, a submission form and submission information are available at the Plant Molecular Diagnostic Lab web page at https://site.caes.uga.edu/alimdl/fungicide-resistance-testing/. See the form at https://site.caes.uga.edu/alimdl/files/2019/02/resistant-profile-form-003.pdf.

    Samples can be shipped to:Plant Molecular Diagnostic Lab

    Department of Plant Pathology

    Tifton, CAES Campus

    Plant Science Building

    115 Coastal Way

    Tifton, GA 31794

    For more information of questions, contact Ali at emran.ali@uga.edu, 229-386-7230 or 229-386-7285.

    Growers are highly encouraged to take advantage of this service. It is very important to know the resistance profile for anthracnose at your location — fungicides that should work and those that will not. If you have questions or need help, contact your local county agent for additional information. It is recommended to overnight samples to the Plant Molecular Diagnostic Lab and to communicate with the lab so it can expect the samples on the day of arrival.

    Fungicide resistance can be devastating, so use these services to ensure that the fungicides you are utilizing are active. Spraying inactive fungicides is the equivalent of spraying water on your strawberry plants. If a fungicide is not active, you waste money on the fungicide, and you can lose your entire crop to disease as well — adding insult to injury.

    This story was from the August edition of VSCNews Magazine. To subscribe, see http://vscnews.com/subscribe/.

  • Organic management methods for squash pests

    A squash bug lays its eggs in a crop.

    By Ayanava Majumdar, Rammohan Balusu and Neil Kelly

    Many pests feed on squash from seedling to harvest. They are generally broken down into two groups: the chewing insects and the sucking insects. Chewing insects of squash consist of common pests like cucumber beetle, squash vine borer larva and pickleworm. Sucking insect pests consist of aphids, squash bugs and whiteflies. The pests a squash grower experiences may depend on location.

    PREVENTION STRATEGIES

    Remember that prevention of pests is the No. 1 goal of organic integrated pest management (IPM) systems. Rapid control after pest establishment becomes a difficult aim later in the production season. Cultural control tactics that include selecting virus-resistant varieties, timely planting and harvest (reduces pickleworm buildup), crop rotation and timely removal of crop debris after harvest (reduces squash vine borer buildup), consistent irrigation and trap cropping are some basic preventive approaches, also called Level 1 control.

    Perimeter trap cropping with Baby Blue and New England Hubbard squash in a mixed system is effective in reducing cucumber beetle and squash bug damage to yellow squash (main crop).

    PEST EXCLUSION FABRIC

    For Level 2 control, growers should use temporary or permanent pest exclusion fabric to create a barrier between insect pests and the main crop. Two lightweight materials tested in Alabama include the Super-Lite Insect Barrier (Gardens Alive, Inc.) and AgroFabric Pro 19 (Seven Springs Farm, Inc.). Both these materials look like lighter versions of the common row cover used for frost protection, but these materials are much lighter with 85 to 95 percent light and rain penetration.

    The trick is to put these light fabrics on low hoops (inverted loops) almost immediately after transplanting or after the seeds have germinated. These materials deflect much of the aphids and squash vine borers that fly early in the season. Squash plants can be grown inside the fabric for several weeks and removed or partially opened when flowering begins. Growers can also release beneficial insects like lacewings and lady beetles under the fabric for controlling accidental pest infestations.

    For both trap crops and pest exclusion tactics, check out the short IPM videos on the Beginning Farm Project channel at www.youtube.com/playlist?list=PLkNoAmOtt___MKj6IBxvWzOdWP0btBq4D.

    INSECTICIDE USE

    Growers also have a wide range of organic insecticides to choose from (Level 3 control). See the Organic Materials Review Institute website (www.omri.org) to find hundreds of approved organic products.

    Remember to scout squash crops for timely pest detection and identification, then use insecticides per the label with equipment that gives good coverage. For example, highly mobile squash bug adults are difficult to control with natural pyrethrin and spinosad, but the flightless small nymphs are far better targets for organic spray applications.

    Several premix insecticides are available commercially today in a variety of packaging, making them affordable for farmers. Squash vine borer and pickleworm larvae are internal pests, which are difficult to manage with topical spray applications. Initiate timely sprays with targeted placement where insect pests are hidden.

    Don’t quit spraying too soon since weather patterns can reduce insecticide persistence. Always spray in the evening hours when bees are not around and so that the solution can dry out overnight. Stop spray applications of organic materials when pests become inactive. You can save on the cost of insecticides and protect natural enemies this way.

    Finally, it is recommended that growers get in touch with Extension personnel in their state to develop an IPM strategy suitable for their farm. Producers in Alabama can download the Farming Basics mobile app to keep in touch with Alabama Extension. Subscribe to the Alabama IPM Communicator e-newsletter (www.aces.edu/ipmcommunicator) to stay informed throughout the season.

  • Technology to Improve Vegetable Production

    Figure 1. Initial design of the low-cost robotic sprayer for precision weed control in vegetable production: main components of the smart sprayer (A) and self-reconfigured and self-adjustable design for easy field deployment in a variety of vegetable fields (B).

    By Yiannis Ampatzidis

    Vegetable growers face a variety of challenges, including pest and diseases, labor shortages and climate change. How can new advancements in technology help growers address these challenges? Can technology improve crops, reduce production costs and protect the environment? How can technological innovations be incorporated into traditional farming to improve production practices?

    In the last few decades, several “smart” technologies have been developed for vegetable production and processing. However, growers are confronted with a variety of challenges when considering adopting new technology or adjusting existing technology. Growers are being offered solutions that might not work in their specific production system or might not be economically feasible. This article presents examples of state-of-the-art technologies that may be used in vegetable production today or in the near future!

    SIMPLIFY SURVEYING

    Field surveys for disease/pest scouting and to assess plant stress are expensive, labor intensive and time consuming. Since labor shortage is a major issue in vegetable production, small unmanned aerial vehicles (UAVs) equipped with various sensors (remote sensing) can simplify surveying procedures, reduce the labor cost, decrease data collection time and produce critical and practical information.

    For example, recently UAVs and remote sensing have allowed growers to constantly monitor crop health status, estimate plant water needs and even detect diseases. The precision agriculture team (@PrecAgSWFREC) at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Southwest Florida Research and Education Center (SWFREC) developed a cloud-based application called Agroview (http://agroview.farm/login.php).

    Agroview can process, analyze and visualize data collected from UAVs and other aerial platforms (e.g., small planes and satellites). This technology utilizes machine learning (an application of artificial intelligence) to detect single plants and assess plant size and stress. Agroview and UAVs were initially used to create plant inventories in citrus (see a video demonstration at https://twitter.com/i/status/1202671242647490560) and to detect specific diseases in vegetables with high accuracy. Early detection and eradication of infected plants is crucial to controlling disease and pest spread throughout the field.

    SMART SPRAYERS

    Most conventional sprayers apply agrochemicals uniformly, even though distribution of pests and diseases is typically patchy, resulting in waste of valuable compounds, increased costs, crop damage risk, pest resistance to chemicals, environmental pollution and contamination of products. Contamination can be related to run-off after application, discharge from drainage and off-target deposition of spray due to wind (spray drift). This contamination can be significantly reduced through optimization of spraying technology.

    Spray drift of agrochemicals occurs during every application and accounts for a loss of up to 50 percent of the agrochemical used. Minimizing the negative impacts of agrochemicals (and spraying technologies) is a major global challenge.

    More than 90 percent of the acreage of crops in the United States are being sprayed with herbicides. It is estimated that $26 billion is spent on herbicides (more than 3 billion pounds) each year. This overuse of chemicals creates herbicide-tolerant weeds and approximately 250 known species of resistant weeds.

    In recent decades, several smart technologies have been developed for pest detection and for optimizing spraying applications. These new spraying technologies have shown an important improvement in efficiency and safety by adopting the latest advances in electronics, artificial intelligence (AI) and automation.

    One example is the See & Spray machine developed by Blue River Technology (www.bluerivertechnology.com) for weed control in arable crops. See & Spray utilizes computer vision and AI to detect and identify individual plants (such as cotton) and weeds and then applies herbicide only to the weeds. See how this technology works at https://youtu.be/gszOT6NQbF8. This machine can reduce the required quantity of herbicide by more than 90 percent compared to traditional broadcast sprayers. However, this technology was designed for arable crops and might not be a cost-effective solution for specific vegetable production systems.

    Another low-cost smart sprayer has been designed and developed by the UF/IFAS team for precision weed management in vegetables. In the initial evaluation experiments, smart technology was able to accurately detect and distinguish weeds from crops and apply chemicals only on specific weed(s), thus avoiding crops and areas without weeds. See a video demonstration of this technology at https://twitter.com/i/status/1045013127593644032.

    Recently, the precision ag team, in collaboration with Abhisesh Silwal (Carnegie Mellon University) and Panos Pardalos (UF), received funding from the U.S. Department of Agriculture and the National Research Foundation (award #2020-67021-30761) to improve and fully automate this smart sprayer. This novel robotic sprayer (or fleet of sprayers) was designed to be self-reconfigured and self-adjustable for easy field deployment (Figure 1). With this design, the robot can reconfigure itself (Figure 1b) to manage weeds in a variety of vegetable fields (e.g., with different row spacing and raised bed sizes).

    ROBOTIC HARVESTING
    Figure 2. Harvest Croo Robotics harvester for strawberries

    Fresh-market vegetables are quickly perishable and virtually 100 percent are hand-harvested. Vegetable growers face increasing shortages of laborers, which in turn, drive up harvest costs. Mechanical and robotic harvesting systems for vegetable growers could simultaneously decrease their dependence on manual labor, reduce harvesting costs and improve overall competitiveness in the market.

    In one example, Harvest Croo Robotics, a Florida company, is developing a robotic harvester for strawberries that does not require growers to radically change the way they currently grow crops. This technology successfully harvested berries during the 2019–20 season. It could address the labor shortage problem and increase grower profit. 

  • Picking Varieties With Profit Potential

    citrus expo

    By Gene McAvoy

    Choosing which variety to plant is one of the most critical decisions that a commercial grower must make each season.

    Variety selection is a dynamic process. In the past, some varieties retained favor for many years. More recently, with advances in plant breeding and the incorporation of new and improved traits for disease resistance and other horticultural characteristics, there is a trend for older varieties to be supplanted by newer cultivars after only a few seasons.

    “Profit” may be the only word needed to describe the importance of variety selection. Profit potential depends on selecting varieties suited to the farm and your target market.

    Selecting the proper variety may be an opportunity to expand a market or overcome certain production obstacles.

    Growers would be wise to heed the old saying: “There is nothing more optimistic than a seed catalog.”

    DO YOUR HOMEWORK

    Study and use reliable results from local performance tests, including on-farm trials, other growers’ experience, vegetable and seed trade literature and university studies. Discuss results of university and seed trade variety trials with the people who performed them.

    On-farm trials will help identify varieties that may be potential candidates for production.

    START SMALL

    When trying new varieties, do so on a small-scale basis but make it a fair test by growing them under the same conditions likely to be encountered in the field. Whether the new varieties work or not, the process of testing them will provide valuable information.

    RECORD RESULTS

    “Mental notes” on yield or overall performance are usually not as accurate as actual measurements. Keeping accurate records of yield and other data is important but often overlooked. To gain the most benefit from on-farm trials, results should be recorded and documented.

    With good records, growers can identify which varieties will perform best in which fields in which season (early, mid or late) and other production conditions (e.g., climate, disease and insect pressure).

    TRY SOMETHING NEW

    Following the maxim “if it ain’t broke, don’t fix it,” growers sometimes identify and stick with favorite varieties. This approach is understandable, but it shouldn’t prevent a producer from trying new varieties.

    Production and market forces increasingly demand that growers establish identities in the marketplace, partly through supplying unique, high-quality products. For growers, changes in consumer preferences can dictate adoption of new and unique varieties to distinguish themselves in the market.

    KNOW YOUR MARKET

    Research the market to clarify what is valued and accepted. Growers should know their target market and be prepared to grow what the market dictates. Keep in mind that most markets tend to see yield as the grower’s concern and quality as theirs.

    In evaluating a new cultivar, these important selection factors should be considered:

    • Marketability: The harvested plant product must have characteristics desired by the packer, shipper, wholesaler, retailer and consumer.
    • Maturity needed to match the cropping season, supply the market and reduce the risk of weather-related crop failure
    • High marketable yield potential
    • Dependable resistance to diseases, insects, stress and physiological disorders (e.g., blossom-end rot)

    In pepper, these qualities include pack-out, shelf life, shape (blockiness), number of lobes, color (both mature color and shade of green for immature fruit), size, firmness and pod wall thickness. More recently, some markets are interested in nutritional quality and taste.

    The tomato market seeks many of these same qualities, including color, shape, flavor, firmness, pack-out, shelf life and shipping and ripening characteristics.

    Variety evaluation should be an ongoing process for growers who wish to remain profitable and competitive.

  • Farmworker Safety During Unprecedented Times

    Growers take steps to protect farmworkers’ health so they can continue to ensure an abundant, safe food supply is available to U.S. consumers. Image source: The Pajaronian

    By Amy Wolfe

    While the country finds itself navigating unprecedented circumstances during the COVID-19 pandemic, growers across the Southeast have continued forging ahead in producing the safest possible food supply. That work has included a variety of challenges, including how best to prevent the spread of COVID-19 on the farm while considering the safety, health and well-being of the agricultural workforce.

    COVID-19 PRECAUTIONS

    There are a variety of precautions to evaluate and implement on the farm to ensure the safety of farmworkers during the COVID-19 pandemic. Owners and management need to consider the following:

    Communicating with Workers

    The need for daily communication with workers is essential. The misinformation available through social media and other outlets has led to critical misunderstandings around how the virus is spread and what steps employers and employees need to take to minimize risk. As such, it is critical that employees receive the following information:

    Social Distancing

    During the start of the shift, breaks and lunch, keep workers at least 6 feet apart. Provide additional seating, such as plastic or folding chairs, to ensure workers are off the ground. Stagger breaks and lunch if additional seating is not available. Stagger meetings and trainings at the start and end of the shift if additional seating is not available.

    In the field, space workers out to provide distance between them. One row should be separating them when planting, pruning, thinning, harvesting or doing other field work. Make more than one pass through a field when harvesting product with equipment.

    Drinking Water for the Crew

    Assign an employee to serve drinking water to crew members from the communal water receptacle. Ensure the worker serving the water has proper personal protective equipment (PPE), including disposal gloves and a face mask or covering. Sanitize the spigot after filling disposable cups each break. Sanitize the spigot if it comes in contact with a reusable water container drinking area (example: mouth of a water bottle).

    Hand soap, paper towels and potable water must always be available in portable restrooms. Image source: Kerkstra Services

    Portable Restrooms and Handwashing

    Assign an employee to sanitize portable restrooms (door handles, locks and toilet seats) and handwashing facilities (spigot, soap dispenser, paper towel dispenser) frequently during the day. Ensure the worker has proper PPE. Provide sanitizing products and train workers on how to properly sanitize. Frequently communicate the expectation that sanitation procedures are followed and assign a supervisory employee to monitor compliance.

    Worker Transportation

    If company vehicles are provided to workers, ensure that those vehicles are being cleaned and sanitized on the inside and outside regularly, ideally once a day. If it is essential to use transportation, such as a van or bus, to transport workers:

    • Sanitize at least twice a day (following employee pick-up and drop-off) all points of contact (seats, seat belts, knobs, doors, handles, buttons, etc.) that employees touch.
    • Ensure ample ventilation and airflow inside the vehicle.
    • If possible, seat workers spaced at least 6 feet apart.Consider additional trips to allow spacing of workers.
    • Assign seating so if a worker becomes ill, it is easy to identify those in proximity and take the appropriate next steps around informing them, as well as asking them to stay home from work for 14 days.

    Sanitizing Equipment and Tools

    More frequent sanitation of all equipment and tools is critical. Ensure teams already responsible for cleaning do so at least daily. Do not forget the following items, which can be overlooked:

    • Tractors, forklifts, ATVs and UTVs, including seats, seat belts, knobs, doors, handles and buttons.
    • Areas of congregation and meeting, both inside and outside. This includeschairs, shade trailers, buckets, refrigerators, coolers, water jugs, vending machines, garbage cans, bottles and containers used daily
    • Employee equipment and tools, including bins and hand tools
    GENERAL FARM SAFETY

    With the emphasis currently on new COVID-19 protocols, don’t overlook other tried-and-true agricultural safety measures. It is essential that one risk isn’t traded for another. With the summer months fast approaching, growers need to be mindful of the potential for heat-related illnesses. Ensure workers have access to ample drinking water and shade and that they are aware of the steps they should take if they begin to experience overheating symptoms.

    In addition, be sure workers using equipment like tractors, forklifts and ATVs receive proper training on safe operation. Training should occur annually and include the process for inspecting the equipment prior to use, the correct operation of the equipment and the protocol for reporting any mechanical issues.

    Lastly, it is important that growers remember to be mindful of the Worker Protection Standard (WPS) and the importance of ensuring workers now receive their appropriate annual training. The WPS was updated by the Environmental Protection Agency in 2016 to include annual training for farmworkers not involved in pesticide application. They need to be provided details on routes and types of exposure, signs and symptoms of pesticide poisoning, first aid care, after-work care of contaminated clothing, field postings and the concept of the re-entry interval, where to find the field worker decontamination site, the contents of safety data sheets, and how to stay out of the application exclusion zone.

    The continued safety and health of farmworkers is paramount. It is critical that growers maintain vigilance with year-round safety issues, as well as consider the unique circumstances now impacting the industry as it navigates through the COVID-19 pandemic.

    Amy Wolfe is president and chief executive officer of AgSafe, headquartered in Modesto, California. AgSafe is a 501c3 nonprofit providing training, education, outreach and tools in the areas of safety, labor relations, food safety and human resources for the food and farming industries. For more information, visit www.agsafe.org, call 209-526-4400 or email safeinfo@agsafe.org.