C.O.R.N. Newsletter: 2020-18

  1. Ohio Department of Agriculture: dicamba use in Ohio ends June 30, 2020

    Author(s): Peggy Hall

    The dicamba roller coaster ride continues today, with a statement issued by the Ohio Department of Agriculture clarifying that the use of XtendiMax, Engenia, and FeXapan dicamba-based products in Ohio will end as of June 30, 2020.  Even though the US EPA has issued an order allowing continued use of the products until July 31, 2020, use in Ohio must end on June 30 because the Ohio registrations for the three dicamba-based products expire on that day.

    As we’ve explained in our previous blog posts here and here, the Ninth Circuit Court of Appeals vacated the registration of the dicamba products on June 3, 2020.  In doing so, the court stated that the EPA had failed to perform a proper analysis of the risks and resulting costs of the products.  According to the court, EPA had substantially understated the amount of acreage damaged by dicamba and the extent of such damage, as well as complaints made to state agriculture departments.  The court determined that EPA had also entirely failed to acknowledge other risks, such as the risk of noncompliance with complex label restrictions, economic risks from anti-competition impacts created by the products, and the social costs to farm communities caused by dicamba versus non-dicamba users.  Rather than allowing the EPA to reconsider the registrations, the court vacated the product registrations altogether.

    The EPA issued a Cancellation Order for the three products on June 8, stating that distribution or sale by the registrants is prohibited as of June 3, 2020.  But the agency also decided to examine the issue on the minds of many farmers:  what to do with the products.  Applying its “existing stocks” policy, the EPA examined six factors to help it determine how to deal with stocks of the product that are in the hands of dealers, commercial applicators, and farmers.  The EPA concluded that those factors weighed heavily in favor of allowing the end users to use the products in their possession, but that use must occur no later than July 31, 2020 and that any use inconsistent with the previous label restrictions is prohibited.

    Despite the EPA’s Cancellation Order, however, the Ohio Department of Agriculture is the final arbiter of the registration and use of pesticides and herbicides within Ohio.  ODA patiently waited for the EPA to act on the Ninth Circuit’s ruling before issuing its guidance for Ohio users of the dicamba products.  In its guidance released today, ODA stated that:

    • After careful evaluation of the court’s ruling, US EPA’s Final Cancellation Order, and the Ohio Revised Code and Administrative Code, as of July 1, 2020, these products will no longer be registered or available for use in Ohio unless otherwise ordered by the courts.
    • While use of already purchased product is permitted in Ohio until June 30, further distribution or sale of the products is illegal, except for ensuring proper disposal or return to the registrant.
    • Application of existing stocks inconsistent with the previously approved labeling accompanying the product is prohibited.

    But the roller coaster ride doesn’t necessarily end there.  Several dangling issues for dicamba-based product use remain:

    • We’re still waiting to see whether the plaintiffs who challenged the registrations (the National Family Farm Coalition, Center for Food Safety, Center for Biological Diversity, and Pesticide Action Network North America) will also challenge the EPA’s Cancellation Order and its decision to allow continued use of the products, and will request immediate discontinuance of such uses. 
    • Bayer Crop Science, as an intervenor in the Ninth Circuit case, could still appeal the Ninth Circuit’s decision, as could the EPA. 
    • All of these orders add complexity to the issue of liability for dicamba damage.  That issue has already become quite controversial, often pitting farmer against farmer and requiring the applicator or damaged party to prove adherence to or violation of the complicated label restrictions.  But the Ninth Circuit’s attention to the risks of adverse impacts from the products raises additional questions about whether an applicator who chooses to use the products is knowingly assuming a higher risk, and whether a liability insurance provider will cover that risk.  For this reason, growers may want to have a frank discussion with their liability insurance providers about coverage for dicamba drift.

    The dicamba roller coaster ride will surely continue, and we’ll keep you updated on the next development. 

    Read the ODA’s Official Statement Regarding the Use of Over-the-Top Dicamba Products here.

    Additional update from Peggy Hall.

    It appears that there will not be an immediate federal order to cease use of dicamba, despite the emergency motion filed by the National Family Farm Coalition last Thursday that asked the Ninth Circuit to void the EPA’s order that allow use of existing stocks.  Since then:

    • The Ninth Circuit Court of Appeals has directed the EPA to respond to the emergency motion, giving the agency until the end of the work day on June 16 to do so. 
    • The court has also directed the Coalition to then file a reply to the EPA’s response, and to do so by the end of the workday on June 18. 

    This suggests that the court will make a ruling after June 18.  For the time being, then, the Court of Appeals has not taken any further action that would disallow ODA’s allowance of the use of dicamba in Ohio until June 30. 

    However, as I mentioned in my last blog post on the Ohio Ag Law Blog, it would be wise for applicators to check in with their insurers to determine whether their insurers will cover a drift incident given the “vacated” registration status of XtendiMax, FeXapan and Engenia.  Some insurers have already indicated that they will not ensure coverage.

    Be aware, also, that Corteva Agriscience (maker of FeXapan) and BASF (maker of Engenia) have filed motions to intervene in the case.  Although it’s doubtful that the court will allow intervention at this point in the process, the motions suggest that the three companies (Bayer Crop Science is already an intervenor in the case) are planning an appeal of the Ninth Circuit’s decision to vacate the registrations.  That appeal would go to the U.S. Supreme Court.

  2. Distribution of waterhemp and Palmer amaranth in Ohio

    Author(s): Mark Loux

    The maps that accompany this article show our current knowledge of waterhemp and Palmer amaranth distribution in Ohio.  These are based on information from a survey of OSU Extension County Educators, along with information we had from samples submitted, direct contacts, etc.  We still consider any new introductions of Palmer amaranth to be from an external source (brought in from outside Ohio) – hay or feed, infested equipment, CRP/cover/wildlife seedings.  Palmer is not really spreading around the state, and as the map shows, we have had a number of introductions that were immediately remediated.  The number of counties where an infestation(s) is being managed is still low, and within those counties, the outbreak occurs in only a few fields still.  Waterhemp is much more widespread in Ohio and is spreading rapidly within the state from existing infestations to new areas via equipment, water, animals, etc.  We do not have Ag Educators in all counties, and even where we do, infestations can occur without us knowing about them.  Feel free to contact us with new information to update the maps.

    Palmer amaranth map 2019 OhioAmong the weed photos sent to the Agronomy Team members for identification, a fair number lately has been for the purposes of “pigweed” identification.  “Pigweed” as used here can refer to waterhemp, Palmer amaranth, spiny amaranth, Powell amaranth, and redroot/smooth pigweed (these two are mostly the same for ID/control purposes).  It’s almost impossible to tell these apart when they are very small, but this gets easier by the time they are 4 inches tall.  Waterhemp and Smooth/redroot pigweed are still the most common.  Waterhemp is smooth all over with a somewhat elongated leaf with smooth edges, and leaves sometimes can be a darker and glossier green than pigweed.  Smooth/redroot pigweed will have a hairy/rough stem (more defined as it gets larger), with relatively nonglossy leaves that are widest in the middle with “rougher” edges.  Various resources are available to help with identification, including our pigweed ID fact sheet and Youtube video.  Identification of pigweeds is not necessarily straight forward, so feel free to contact your local extension educator or OSU weed scientists (loux.1@osu.edu or ackley.19@osu.edu) for help with identification. 

  3. Changes in status of dicamba product labels for Xtend soybeans – a recap

    Author(s): Mark Loux

    On June 3, the US 9th Circuit Court of Appeals issued a decision in a case concerning the use of dicamba on Xtend soybeans.  This decision voided the labels for XtendiMax, Engenia, and FeXapan that allows use on Xtend soybeans.  Tavium was not included in this decision, because it was not approved for use when the case was initially filed.  Several excellent articles covering this decision can be found here on the OSU Ag Law blog (https://farmoffice.osu.edu/blog).  EPA stated on June 8, providing further guidance about what this decision means for the use of dicamba for the rest of this season.  The gist of this decision was the following:  

    “EPA’s order addresses sale, distribution, and use of existing stocks of the three affected dicamba products – XtendiMax with vapor grip technology, Engenia, and FeXapan.

    1. Distribution or sale by any person is generally prohibited except for ensuring proper disposal or return to the registrant.
    2. Growers and commercial applicators may use existing stocks that were in their possession on June 3, 2020, the effective date of the Court decision. Such use must be consistent with the product’s previously-approved label, and may not continue after July 31, 2020.”

    ODA subsequently issued a statement regarding the registration and use of these products in Ohio, stating that any application must happen before July 1, 2020.  Partial text from this statement:

    “The registration of these products (XtendiMax, FeXapan, and Engenia) in Ohio expires on June 30, 2020. After careful evaluation of the court’s ruling, US EPA’s Final Cancellation Order, and the Ohio Revised Code and Administrative Code, as of July 1, 2020, these products will no longer be registered or available for use in Ohio unless otherwise ordered by the courts.

    While the use of the already purchased product is permitted in Ohio until June 30, 2020, the Court’s decision and US EPA’s order make further distribution or sale illegal, except for ensuring proper disposal or return to the registrant. Application of existing stocks inconsistent with the previously approved labeling accompanying the product is prohibited. If you have questions about returning unused products, please reach out to your pesticide dealer’s representative.”

    So what is the impact of all of this, and how do we adjust herbicide programs to deal with it?  Some things to consider:

    - The majority of the POST applications on Xtend soybeans occur prior to the end of June anyway, although some certainly do occur in July.  And while XtendiMax, FeXapan, or Engenia cannot be applied after June 30, the previous label restrictions are also still in place – POST application must occur before the R1 stage or no later than 45 days after soybean planting, whichever occurs first.  So if the soybeans were planted by May 15, products would have to be applied prior to June 30 anyway, and if planted later, they would have to be applied before R1 or before June 30, whichever occurs first. 

    - It’s important to keep in mind that the emergence of most summer annual weeds peaks in early to mid-June and then starts to decline, although there can be later flushes of weeds with rainfall events especially.  So except where soybeans are planted late and are still small, applying POST herbicides in mid to late June catches most of the weeds and provides effective control.  We expect the soybean canopy to have developed adequately to suppress weeds emerging after the POST application.  Based on our research, this can work even in later-planted soybeans just due to the fact that weed emergence slows down towards the end of June. 

    - Given how difficult it can be to find suitable weather to apply the dicamba products, we suggest looking for a window to apply and doing so.  We have 15 days left in June to apply legally, and probably more like seven days factoring in weather and application stewardship requirements.  Waiting until the end of next week is possibly not a great plan.

    - Registration of Tavium, the premix of s-metolachlor and dicamba with VaporGrip, was not affected by this decision and remains a legal option even after June 30.  Tavium can be applied through the V4 soybean stage, or through 45 days after planting, whichever occurs first. 

    Ragweed- Without the availability of dicamba to use POST, the Xtend soybean becomes an old school Roundup Ready soybean.  THE primary POST option would be a mix of glyphosate with an ALS inhibitor (Classic, FirstRate, etc.) or PPO inhibitor (Flexstar and generics, Cobra/Phoenix, Ultra Blazer).  These would also be the options where a second POST application is necessary after June 30.  Not all of these may be viable in July due to soybean growth stage, PHI, or crop rotation restrictions

    - Weeds of greatest concern here are marestail, waterhemp, Palmer amaranth, giant ragweed, and also common ragweed in NW Ohio.  These five weeds are mostly glyphosate and ALS resistant in Ohio, and PPO resistance is fairly common in waterhemp and also occurs in some common ragweed and Palmer amaranth populations.  None of these mixtures will be effective for POST marestail control.  Effectiveness on the other weeds will be variable among and within fields across Ohio.  Some giant ragweed populations are still partially controlled by glyphosate, so plant size and glyphosate rate and the number of applications make a difference.  We would expect a complete lack of waterhemp control in some fields. 

    - Another option would be to replant Xtend soybean fields with another type of soybean that provides for the POST options of 2,4-D choline and/or glufosinate – Enlist, LibertyLink, or LLGT27 – should seed still be available.  This strategy should be used for double-crop soybeans also unless weeds can be handled well enough with the mixtures mentioned above.

  4. True Armyworm Infestations

    We received many reports of true armyworm infestations in wheat, barley, and corn. These are black or green caterpillars with stripes along the side and orange heads.  In the spring, true armyworm moths migrate from the south and lay eggs in grasses such as forage and weed grasses, winter wheat and barley, and rye cover crops.  When the eggs hatch, the larvae can significantly damage wheat and barley before then moving to young corn. Usually, moth flights occur in April, but we may have had a second peak the first or second week of May—it’s likely the caterpillars feeding now are from this later flight. Right now, wheat, barley, and corn should be inspected for true armyworm populations. Armyworms like to hide during the day and feed at night, so scouting should occur at dusk or dawn, and/or on cloudy days.

    ArmywormCorn: True armyworm in corn cause the most damage when planted in no-till grassy fields, such as a rye cover crop.  In this case, after feeding on the cover crop, the caterpillars shift onto the emerging corn.  The name armyworm comes from the caterpillars’ behavior of migrating en masse from one location to another. Thus, one should pay particular attention to cornfields adjacent to wheat fields that may have supported a high armyworm population, especially the first several rows into the cornfield. As the wheat matures and dries down, it could stimulate the caterpillars to move.

    One may only need to treat the edge of the field closest to the wheat field from which the caterpillars are marching. If armyworms are found in a cornfield, check for the percentage of plants damaged in 5 sets of 20 plants.  If more than 10% of the stand has feeding damage, it may indicate a large infestation, and the field should be re-checked in a few days to see if defoliation is increasing. If defoliation has increased and plants have two or more caterpillars per corn seedling, an insecticide application may be necessary. However, if most larvae are longer than 1 inch, then much of the feeding is complete as the caterpillars will begin to pupate. Also, look for the presence of diseased (black and shriveled) or parasitized caterpillars (having a few or several small, white egg cases on their body)—if found, do not include them in your counting.Armyworm caterpillars  

    If defoliation exceeds 50%, even a rescue treatment may not recover the field without a significant impact on yield.  According to the Handy Bt Trait Table (https://agrilife.org/lubbock/files/2020/02/BtTraitTable_FEB_2020.pdf), only the Vip3A (e.g., Viptera) Bt trait is effective against true armyworm.  Insecticidal seed treatments may offer some control but can be overwhelmed with high populations. Plus, insecticidal seed treatments last only about 4-6 weeks after planting.Fecal pellets or frass

    Wheat, Barley, and other Small Grains:   Examine a 4 square foot area in 5 locations throughout the field.  If the average of caterpillars less than 1 inch long is greater than 16, or if head-cutting is occurring, treatment may be necessary. Keep in mind that more mature wheat can tolerate a lot of armyworm feeding.  Fields defoliated in Feekes 11.3 growth stage will suffer less yield loss from those defoliated at earlier growth stages. As with corn, watch for diseased or parasitized armyworms.

    Soybeans: True armyworms CANNOT survive on soybean. They are grass feeders, and any broadleaf plants are a poor food source.  Spraying soybean for true armyworms are not needed. 

    Insecticides: Many foliar insecticides are available for control of true armyworm. If applying in small grains, be careful of the pre-harvest interval (PHI). A long PHI may prevent a timely harvest.    

  5. Wheat Harvest Preparation: Grain Bin Edition

    Author(s): Clint Schroeder

    The 2020 Ohio wheat harvest is rapidly approaching. Now is the time to prepare for a successful harvest. Before the combine goes to the field, a key component will be to have grain handling and storage facilities adequately sanitized. Taking the proper steps now should help eliminate insect infestations that can significantly reduce grain quality or salability.

    The majority of insect infestations that occur in stored grains are a result of migration into the bin. These insect populations will be present in piles of spilled grain from the previous year, livestock feed in the area, litter, and weed growth. Newly harvested wheat can also be contaminated when it comes in contact with infested grain that was not cleaned from the combine, trucks, wagons, augers, dump pits, or grain leg buckets. Another source of contamination can be carryover grain in a bin that was not correctly emptied.

    Proper sanitation begins outside the bin. Brush/sweep or vacuum out any grain left in the combine, wagons, or grain carts. Remove all vegetation that grows within ten feet of the bins. Then spray this area with a residual herbicide to prevent regrowth. Remove any grain spills or other debris that might have accumulated during the load out of the previous crop. This step will minimize the habitat available and make migration to the bin more challenging.

    Inside the bin, it is crucial to make sure that there was no grain left from the previous crop. Thoroughly sweep or vacuum any area that grain could potentially be sitting on, which includes any ledges, ladders, or braces. Remove all dust and debris from fans, aeration ducts, and under slotted floors (when possible). Insects may remain in these hard to clean areas. While the bin is empty, an insecticide application should be completed to combat this potential problem. The treatment will help create another barrier for insects that try to migrate into the bin, but should not be used as a replacement for proper sanitation. The best time to apply insecticides to empty bins is two to three weeks before harvest. Some of the products that can be used for this application are Diacon II (s-methoprene), Storcide II (deltamethrin and chlorpyrifos-methyl (3 ppm)), Tempo 20WP (cyfluthrin), Tempo SC Ultra (cyfluthrin) or diatomaceous earth products. These products can also be applied to the external walls of the bin to create a secondary barrier. It is critical to read the full product label and follow all label instructions.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.


Aaron Wilson (Byrd Polar & Climate Research Center)
Alan Leininger (Educator, Agriculture and Natural Resources)
Amanda Bennett (Educator, Agriculture and Natural Resources)
Amanda Douridas (Educator, Agriculture and Natural Resources)
Andy Michel (State Specialist, Entomology)
Anne Dorrance (State Specialist, Soybean Diseases)
Barry Ward (Program Leader)
Beth Scheckelhoff (Educator, Agriculture and Natural Resources)
Boden Fisher (Water Quality Extension Associate)
Brigitte Moneymaker (Water Quality Extension Associate)
Bruce Clevenger, CCA (Educator, Agriculture and Natural Resources)
Chris Zoller (Educator, Agriculture and Natural Resources)
Clifton Martin, CCA (Educator, Agriculture and Natural Resources)
Clint Schroeder (Educator, Agriculture and Natural Resources)
Curtis Young, CCA (Educator, Agriculture and Natural Resources)
David Marrison (Educator, Agriculture and Natural Resources)
Dean Kreager (Educator, Agriculture and Natural Resources)
Dennis Riethman (Educator, Agriculture and Natural Resources)
Ed Lentz, CCA (Educator, Agriculture and Natural Resources)
Elizabeth Hawkins (Field Specialist, Agronomic Systems)
Eric Richer, CCA (Educator, Agriculture and Natural Resources)
Gigi Neal (Educator, Agriculture and Natural Resources)
Glen Arnold, CCA (Field Specialist, Manure Nutrient Management )
Greg LaBarge, CPAg/CCA (Field Specialist, Agronomic Systems)
Hallie Williams (Educator, Agriculture and Natural Resources)
Harold Watters, CPAg/CCA (Field Specialist, Agronomic Systems)
Jason Hartschuh, CCA (Educator, Agriculture and Natural Resources)
Jeff Stachler (Educator, Agriculture and Natural Resources)
Jeffory A. Hattey (Professor)
John Barker (Educator, Agriculture and Natural Resources)
Lee Beers, CCA (Educator, Agriculture and Natural Resources)
Les Ober, CCA (Educator, Agriculture and Natural Resources)
Mark Badertscher (Educator, Agriculture and Natural Resources)
Mark Loux (State Specialist, Weed Science)
Matthew Romanko (Water Quality Extension Associate)
Matthew Schmerge (Educator, Agriculture and Natural Resources)
Mike Estadt (Educator, Agriculture and Natural Resources)
Mike Gastier, CCA (Educator, Agriculture and Natural Resources)
Nick Eckel (Educator, Agriculture and Natural Resources)
Peggy Hall (Field Specialist, Agricultural & Resource Law)
Pierce Paul (State Specialist, Corn and Wheat Diseases)
Rachel Cochran (Water Quality Extension Associate)
Rich Minyo (Research Specialist)
Sarah Noggle (Educator, Agriculture and Natural Resources)
Stephanie Karhoff (Educator, Agriculture and Natural Resources)
Steve Culman (State Specialist, Soil Fertility)
Ted Wiseman (Educator, Agriculture and Natural Resources)
Wayne Dellinger, CCA (Educator, Agriculture and Natural Resources)
Will Hamman (Educator, Agriculture and Natural Resources)


The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information, visit cfaesdiversity.osu.edu. For an accessible format of this publication, visit cfaes.osu.edu/accessibility.