Traditional cotton with dicamba drift injury on one row vs healthy. Photo – Jay Ferrell
The past two months have been life altering for many farmers in the southeast, especially the Florida Panhandle. Hurricane Michael made landfall in the Panhandle on October 10th and left a path of destruction spanning several counties as it continued into Southwest Georgia. With the aftermath of Michael, farmers from Walton to Gadsden counties were left without power and severe damage to crops and equipment.
On October 31st, the Environmental Protection Agency (EPA) announced that it was extending the registration of Dicamba for over-the-top (OTT) use for weed control in transgenic cotton and soybean. Dicamba products approved for use on dicamba-tolerant crops include Engenia (BASF), XtendiMax (Monsanto), and FeXapan (Corteva). This announcement came during a period when much of Jackson and Calhoun Counties, a large cotton producing area, wwere without power. The purpose of this article is to help promote the announcement and raise awareness regarding label changes for products approved for use in Dicamba-tolerant cotton and soybean. Another product to follow is chlorpyrifos, better known as Lorsban, which, depending on outcomes of legal/regulatory proceedings, will likely still be available for use during the 2019 season.
Dicamba
Along with the EPA announcement of the two-year extension in registration of dicamba products used in row crops (now through 2020), new restrictions were revealed that will be integrated into product labels. It is imperative that growers read these labels and understand what these changes mean regarding product use. Dicamba is currently registered for OTT use in cotton and soybean in 34 states, including Florida, Georgia, and Alabama.
In 2019, only restricted use pesticide applicators will be allowed to make applications. The purchase and application of dicamba products used on herbicide tolerant crops will not be permitted by those without a pesticide license and the appropriate category, even under the supervision of a licensed applicator. This means that authorized purchasers on an applicators license will no longer be able to purchase the products, only the certified applicatorthemselves. Everyone must now have their own license if they wish to buy or apply these products registered for use on Dicamba-tolerant crops. Depending on their situation, Florida growers will be required to have a Private Applicator or commercial license with the Row Crop category. Obtaining a license means individuals must pass the two necessary pesticide exams with at least a 70 percent, the Core exam and the category exam (Private or Row crop). Exams can be administered at your local Extension Office, but please call ahead to make an appointment. They can also help you decide which license designation (private or commercial) bests applies to your situation. On top of having a restricted use pesticide license, applicators will also be required to attend a 2019 dicamba training, which will be similar to what was provided in March 2018. All individuals who will want to purchase or apply these products (or want the future option) during the 2019 season will need to attend the new dicamba training, regardless of if they attended the one in 2018. A training date has not yet been selected for Florida, but it will likely be a similar timeframe to the 2018 training. Early spring probably around March, using a web format, broadcast from one central location to participating Extension Offices. The date will be announced once the Florida Department of Agriculture and Consumer Services (FDACS) has finalized the specifics, stay in contact with your local Extension Office.
The training will address updates to product labels such as the postemergence application window, number of applications, buffer zones, sensitive areas, application hours, record keeping, spray solution pH, and more.
Since 1965 chlorpyrifos has been used as a pesticide in the agricultural sector. It is commonly used as an insecticide in the production of crops such as corn, peanut, and soybean, among others. It is recognizable to most farmers under the brand name Lorsban. Chlorpyrifos is a cholinesterase inhibitor which can cause problems in people exposed to high enough doses. This means that it can overstimulate the nervous system resulting in symptoms such as nausea, dizziness, and confusion.
Since 2000, the EPA has evaluated and modified the use of chlorpyrifos several times. In 2017, the EPA denied a petition requesting to revoke of all pesticide tolerances (residue level allowed in food) for the chemical and for the cancellation of all chlorpyrifos registrations. On August 9, 2018, the Ninth Circuit Court of Appeals ordered the EPA to ban chlorpyrifos within 60 days. In September the EPA appealed the decision, and the Department of Justice asked the Ninth Circuit to reconsider its opinion. Over 100 days have passed since the ban was requested with the 60-day deadline, and it appears that chlorpyrifos will remain available for use until the legal/regulatory proceedings are finished.
A few weeks ago I was lucky enough to attend North Carolina State’s Tomato Field Day, at the Mountain Horticultural Crops Research and Extension Center in Mills River, NC. Every summer crowds flock from all over the Southeast to learn what’s new in the world of tomatoes. Since it’s not always convenient for you to drop what you’re doing to make a road trip to North Carolina, I’ll highlight something I learned from the field day.
Stink Bug Control by Dr. Jim Walgenbach
Distribution
The brown marmorated stink bug (BMSB) was introduced into the United States from Asia. The insect pest was first found in Pennsylvania and is suspected to have made its way to the US in packing material. BMSB was first reported in 2009 in Hillsborough County, FL and since been found in additional Florida counties. It has a wide host range including fruits, vegetables, and ornamentals.
Fifth instar nymph of the brown marmorated stink bug on raspberry in Allentown, Pennsylvania. Photo Credit: Gary Bernon, USDA-APHIS
Identification
BMSB has a typical stink bug body shape and size with a mottled brown coloring. The key identification feature is alternating dark and light bands on the last two antennal segments.
Trissolcus japonicus adults. Female to the left; male to the right. Photo Credit: FDACS – DPI
Biological Control with Natural Enemies
Dr. Walgenbach’s team is currently researching the impact of suppressing BMSB populations by native predators such as: katydids; jumping spiders; earwigs; and lady beetles. Current observations indicate only a minor effect from these predators on BMSB.
BMSB egg masses parasitized by T. japonicus. Photo Credit: Matt Lollar, University of Florida/IFAS Extension.
Trissolcus japonicus Assessment
A regional effort has been implemented to monitor the introduction, spread, and efficacy of the Asian parasitoid Trissolcus japonicus. Trissolcus japonicus is a tiny wasp that parasitizes the eggs of various stink bug species. It was first collected from China and brought back to quarantine facilities in the US for evaluation, as a potential biological control agent. Host-specific tests have indicated that T. japonicus prefers to parasitize BMSB eggs over eggs of other stink bug species. It is suspected that release permits for the wasp will be available from the USDA in the near future.
Fungicide resistance or reduced efficacy is a concern when managing peanut diseases, especially the foliar diseases early and late leaf spot. Managing these concerns requires an integrated approach with constant monitoring of the product’s efficacy and application programs to avoid resistance selection. Two common resistance management strategies are alternating (or rotating) and mixing fungicide product modes of action (MOA). It has been indicated that MOA mixtures are a more sustainable strategy for resistance management than alternating, but they may be costlier as they tend to increase the spray program’s number of fungicides. So, it is important to understand the value of these two strategies especially when using products that have a moderate to high risk for resistance selection.
A recent study explored the value of these strategies using the fungicide products azoxystrobin (Abound 2.08), pyraclostrobin (Headline 250 SC) and tebuconazole (TebuStar 3.6L). All these products are off patent and considered medium to high risk for leaf spot resistance or reduced sensitivity. The study consisted of various spray programs that had five applications of chlorothalonil (Chloronil 720) at 30, 44, 72, 100 and 114 days after planting (DAP). The at-risk products were then applied at approximately 58 and 86 DAP either alone (alternation program) or in combination with chlorothalonil (mixture program). The study was conducted at two locations in Marianna and Citra, FL during the 2017 season. The mixture programs generally had higher yields than the alternation programs (4 times out of 6), however, only one of these yields was significantly different (Fig 1). Both strategies provide significant yield savings compared to the untreated control plots (data not shown).
Figure 1. Yield results from the various fungicide alternation and mixture programs at the two locations. Fungicide products consisted of azoxystrobin, pyraclostrobin, tebuconazole and chlorothalonil. All programs consisted of 5 applications of chlorothalonil with the products indicated on the x-axis applied alone or in combination with chlorothalonil at 58 and 56 days after planting. The yield was significantly greater for the mixture program compared to the alternation in the pyraclostrobin treatments for the Marianna location.
Identifying the pathogen population present is a key component when assessing these two strategies. Location populations varied with late leaf spot being the primary pathogen in Marianna, and early leaf spot in Citra (Fig. 2). It is also important to note that significant pressure was also present from late leaf spot and rust in Citra as well. This variation in pathogen population could be one possible reason for the inconsistencies observed between these strategies at each location. It does seem apparent that in situations where multiple pathogens are present that alternations are not as effective as mixtures.
Figure 2. Disease incidence percentages in the untreated control treatments for Citra and Marianna, FL. Early leaf spot, late leaf spot, and rust were rated separately on leaflet samples (48 leaflets/treatment). Disease incidence shown represents average seasonal incidence recorded in the locations during 2017.
Mixing fungicide MOA appears to be the optimal strategy for disease control, yield savings and managing fungicide resistance. However, alternating MOA is also a successful strategy, but its efficacy appears to be highly dependent on the pathogen populations present. Regardless of the strategy chosen, disease control and yield savings were improved with these strategies compared to the untreated plots. Both strategies will help sustain the efficacy of a fungicide product, and if cost is an issue then alternating modes of action in a program is better than repeated applications of a product alone. It should be noted that when using generic products like these, the average cost only varied by approximately $2.50 per acre. The cost of mixtures will depend largely on the mixing partners used, and with some planning these costs can be minimized.
Peanut farmers will have a new leaf spot fungicide option available soon from Syngenta called Miravis.
Syngenta has successfully completed the registration process with the Florida Department of Agriculture for a new fungicide for Florida peanut farmers called Miravis. Miravis is the brand name for Syngenta’s fungicide with the active ingredient Pydiflumetofen, which is a group seven fungicide product.
The following key information is provided on the Miravis label for use in peanut production:
Miravis is a broad-spectrum, preventative fungicide for use in the control of many important plant diseases. In peanuts these diseases include: Early leaf spot (Cercospora arachidicola), Late leaf spot (Cercosporidium personatum), Pepper spot (Leptosphaerulina crassiasca), and Web blotch (Phoma arachidicola) with supression of Sclerotina Blight (Sclerotina spp.) when applied prior to disease development at the recommended rate of 3.4 oz/acre. Miravis may be applied by ground, air, or chemigation, with a pre-harvest interval (PHI) of 14 days.
Dr. Bob Kemerait, University of Georgia Extension Plant Pathologist provided some highlights from his research of Miravis use in peanut:
By all accounts, Syngenta is ready to launch Miravis fungicide for peanut growers this season. There will be a very limited supply for the tri-state area (Georgia-Florida-Alabama) in 2018, perhaps enough to treat between 100 – 200 thousand acres.
Here are a few key points:
Miravis is in the “SDHI” (succinate dehyrdogenase) class of chemistry, which also includes fungicides like Convoy (flutolanil), solatenol (a component of Elatus), fluopyram (Velum) and fluxapyroxad (a component of Priaxor). The SDHI class is quite variable and diverse.
The mode of action of SDHI fungicides is to disrupt electron transport in the mitochondria of the fungus, thus depriving the pathogen of ATP and energy.
The SDHI class is diverse, but not all things all the time. For example, flutolanil (Convoy) is excellent on white mold but does not touch peanut leaf spot diseases. MIRAVIS is excellent for control of leaf spot diseases, but does NOT control soilborne diseases like white mold or Rhizoctonia limb rot, or peanut rust.
Because MIRAVIS is excellent on leaf spot diseases, but not used for soilborne disease control, Syngenta will promote use as a tank-mix with Elatus; thus providing strong, broad-spectrum disease control.
Syngenta has collaborated with researchers and Extension from UGA, UF/IFAS, Auburn, Clemson, and other land-grant institutions to develop Miravis for use on peanuts. Because of this, we have significant experience with the product.
Currently, a MIRAVIS/Elatus program from Syngenta is a 5-spray program. The MIRAVIS (3.4 fl oz/A) is mixed with ELATUS (9.5 fl oz if applied twice or 7.3 fl oz if applied three times in the season) at approximately 50 and 80 days after planting.
The other two (3-Elatus program) or three (2-Elatus program) fungicide applications are something like chlorothalonil or Alto/chlorothalonil applied at 28, 104 and 120 days after planting.
Fungicide resistance management is especially important for Miravis because of mode of action and reduced sprays (5 versus 7 in a “typical” program
As of June 21st, there has been no word on cost yet.
Temperature inversions form a kind of air layering or stratifying effect. It becomes visible when smoke or fog rises and then seems to abruptly hit an invisible ceiling. Credit Judy Biss
Farmers and ranchers must manage traditional business practices to be successful, but they also deal with the many challenges of ever changing weather. Rain, wind, and temperature are important and obvious aspects of weather that producers track on a daily basis, but there are other, not so obvious weather features that affect operational management as well. One of these is a phenomenon called “temperature inversions.”
What is a Temperature Inversion?
Most of the time, if you were to take the air temperature at measured intervals starting from the ground, moving straight up in to the air, the temperature would be warmer at ground level than it is at higher levels over your head. A temperature inversion is simply the reverse of this gradient – the temperature of air at ground level is cooler than the air above it. These inversions occur naturally and most often in the late evening to early morning hours when there is little to no wind. Temperature inversions form a kind of air layering or stratifying effect. If you have ever seen smoke rise and then seemingly, and abruptly, hit an invisible ceiling, you have probably witnessed a temperature inversion.
Why are Temperature inversions important?
Temperature inversions are important because the air layering effect they cause changes the anticipated dissipation of pesticide spray solutions used by agricultural producers. Inversions also affect the movement of smoke from prescribed fires used by land managers. Under a temperature inversion, spray solutions and smoke have the potential to move great distances offsite instead of dissipating and diluting under normal atmospheric conditions. To make a long story short, agricultural producers and land managers do not want their pesticide spray solutions or smoke to move offsite in such a way that could negatively affect non-targets areas. Minimizing pesticide drift is a critical and routine part of pesticide application procedures. There are a number of techniques pesticide applicators use to reduce pesticide drift. One of these techniques is being aware of atmospheric temperature inversions. This is especially important when using organo-auxin herbicides that have characteristics making them more volatile, and thus more affected by air currents. Additionally, in light of the new herbicide application rules for dicamba resistant cotton and soybean varieties, managing pesticide drift is a critical part of stewardship of these new herbicides.
Detecting and Managing Temperature Inversions
Properly managing pesticide drift and smoke from prescribed fire includes using a number of best management practices by trained applicators and managers. Being aware of temperature inversions is only one of the variables they incorporate into their management decisions every day. Some herbicide labels have sections dedicated to explaining the importance of not spraying in areas where temperature inversions exist, and list ways to detect the presence of an inversion. See for example, the herbicide Engenia® by BASF. This is one of the herbicides approved for use on the new dicamba resistant cotton and soybean varieties. Before herbicides approved for use on these new plant varieties can be used, the pesticide applicator must attend a specialized trainingon proper stewardship of these products.
Measure air temperature at 6–12 inches above the soil and at 8–10 feet above the soil. An inversion exists if measured air temperature at 8–10 feet above the soil is higher than the measured air temperature at 6–12 inches above the soil. Be sure the instrument is shaded and not influenced by solar heating.
Morning dew
Morning fog (indicates that an inversion existed prior to fog formation)
Smoke or dust hanging in the air or moving laterally
Overnight cloud cover is 25% or less
Inversions can begin forming three to four hours before sunset and can persist until one to two hours after sunrise
This 3 minute video from the University of Minnesota Extension, provides great information on temperature inversions and how to detect them.
For additional resources on the topic of Temperature Inversions and Pesticide Drift Management, please see the following publications:
Last year, the Environmental Protection Agency (EPA) registered new dicamba herbicide product formulations for making applications to dicamba tolerant cotton and soybean crops. As a result, many states were overwhelmed with drift complaints regarding sensitive crops. This led to the 2018 EPA announcement requiring that anyone who wishes to apply dicamba to dicamba tolerant crops MUST participate in an auxin herbicide training before making applications in 2018.
[warning]This training is required of anyone applying newer dicamba products registered for use on dicamba tolerant cotton and soybeans.[/warning]
Product examples includeXtendiMax, Engenia, and FeXapan. Applicators using older dicamba formulations in other crops (corn, forages, small grains, sorghum, and turf) can still apply dicamba products without having this training but thoseproducts CANNOT be used on the dicamba tolerant crops. If you have questions regarding the use of these products or if you need the training, call your local Extension Office before making any applications.
On March 16, Extension Offices from across the state hosted an online two-hour dicamba training, which was broadcasted live from Gainesville. This training was overseen by the Florida Department of Agriculture and Consumer Services (FDACS), who determined that the CEU form received from completion of this training would serve as the official documentation of attendance. If applicators desire to use the form for CEUs towards renewal of their pesticide license, they are required to keep an additional copy in their possession as proof of completing the dicamba training.
The training was recorded live and made available to all participating Extension Offices (see below). If you plan to make dicamba applications to dicamba tolerant cotton or soybean, you MUST complete this training before making any applications. The training is not required before planting dicamba genetics, but without the training dicamba cannot be sprayed on the crop. If you plan to spray the crop with dicamba, or want the weed control option later in the season, the training is mandatory.
[important]The recorded training has been made available to all participating Extension Offices. Applicators are required to watch it at the Extension Office, where it can be proctored by an agent who is a certified CEU provider and can issue/sign the CEU form. There are no exceptions, you must watch the training at an Extension Office. In the Panhandle, participating Extension Offices with access to the training include: Calhoun, Escambia, Gadsden, Holmes, Jefferson, Okaloosa, Santa Rosa, Walton, and Washington Counties. Contact information for the different offices can be found using the following link: Florida County Extension Offices.[/important]
