Dicamba Approved for Over-the-Top Use 2021 and Beyond

Source: Agweb.com

Tuesday, Oct. 27, 2020, the Environmental Protection Agency (EPA) announced it will approve three of the new dicamba formulations for over-the-top use for five years, according to EPA Administrator Andrew Wheeler. The herbicide is labeled for use in soybeans and cotton with the trait that confers tolerance to dicamba.

The specific formulations include Xtendimax VaporGrip Xtra, Engenia and Tavium. The registration starts next year (2021) and runs through 2025. The administrator said they opted for a five-year registration, which is typical for pesticides, instead of a two-year like dicamba has experienced in the past because they had more data to base this decision upon.

“EPA will register dicamba for over-the-top use on dicamba tolerant cotton and soybeans, this decision provides a five-year registration to provide certainty to growers,” Wheeler says. “EPA. has determined that these registrations address the concerns outlined in the June 9th Circuit Court of Appeals decision.”

The administration said it reviewed 65 new studies when making this decision, reviewed all literature and consulted with experts before making this decision.

In approving the herbicide for use in cotton and soybeans, EPA provided the following changes to the herbicide labels. These changes, and all label instructions, must be followed for legal use:

  • Downwind buffer of 240′ is required and a buffer of 310′ required where listed species are located.
  • Over-the-top application of dicamba of soybeans prohibited nationwide after June 30, and after July 30 in cotton.
  • An approved pH buffering agent will be required to be mixed for application to lower volatility. Buffering agents are registered with the EPA and must be documented each use.
  • Opportunities for growers to use hooded sprayers to reduce buffers.
  • States can expand over-the-top use to meet local needs by working with EPA.

“All of these efforts will help ensure there are not negative impacts on other farmers’ lands,” Wheeler continued. “States can further restrict, but they have to work with us and file the appropriate requests with EPA. We’re trying to have a national program here, we’re responding the the court’s concerns with a national cutoff.”

Dicamba’s use was hotly contested earlier this year. An appeals court vacated the product’s use in early June, which was followed by an exemption for use of stocks on-hand for farmers by EPA. The announcement brough confusion and brought dicamba’s compliance with the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) under the microscope. EPA took those concerns into consideration while making this decision.

“The economic damage that would result from not being able to use dicamba herbicides would be tremendous,” said Ken Fountain, National Cotton Council chairman. “We greatly appreciate EPA’s timely issuance of a new five-year label for the critical crop protection product for cotton farmers.”

Some have already expressed concerns about EPA’s most recent announcement.

“Rather than evaluating the significant costs of dicamba drift as the 9th Circuit told them the law required, EPA rushed re-approval as a political prop just before the election, sentencing farmers and the environment to another five years of unacceptable damage,” said George Kimbrell, legal director at the Center for Food Safety. “Center for Food Safety will most certainly challenge these unlawful approvals.”

This story will be updated with quotes and information as it becomes available.

Preharvest Herbicide Treatments

Source:  Mark Loux, OSU

Information on preharvest herbicide treatments for field corn and soybeans can be found in the “Weed Control Guide for Ohio, Indiana, and Illinois”, at the end of these crop sections (pages 72 and 143 of the 2020 edition).  Products listed for corn include Aim, glyphosate, and paraquat, and for soybeans include Aim, paraquat, glyphosate, and Sharpen.  Some dicamba products are also approved for preharvest use in soybeans, and some 2,4-D products are approved for use in corn, and these are not listed in the guide.  The basic information for these follows:

Dicamba – soybeans:  Apply 8 – 32 oz/A (4 lb/gal products) as a broadcast or spot treatment after soybean pods have reached mature brown color and at least 75% leaf drop has occurred; soybeans may be harvested 14 days or more after a pre-harvest application; do not use preharvest-treated soybean for seed unless a germination test is performed on the seed with an acceptable result of 95% germination or better; do not feed soybean fodder or hay following a preharvest application of this product.

2,4-D – corn:  Labels vary with regard to types of corn that can be treated (some indicate no sweet corn) and based on whether crop is being grown for seed.  Apply after the hard dough (or dent) stage when silks have turned brown.  Weed seed production can be suppressed if applied prior to the flowering stage.  Allow 14 days between application and grain harvest.  Do not forage or feed corn fodder for 7 days after application.

Preharvest herbicide treatments are primarily intended to suppress/kill and dessicate weeds that can make harvest more difficult.  Products with contact activity will cause faster dessication and leaf drop of weeds, but may be less effective at killing weeds compared with systemic products.  Effective dessication with contact herbicides may still require a wait of a week or more following application, and this can can vary by weed.  The maximum paraquat rate is well below the rate required to actually kill large weeds, but it is still probably most effective for dessication of morninglory.  Glyphosate is not likely to be effective on marestail and waterhemp, and many giant ragweed populations, whereas dicamba or 2,4-D may with enough time between application and harvest.  The first frost will usually provide results similar to herbicides, so in a situation where crop maturity is delayed or the infested field can be harvested later in fall, consider whether a herbicide treatment is actually needed.  Preharvest treatments can also be effective for control of warm season perennials, and the systemic herbicides will be most effective where this is the goal.  Keep in mind also that for weeds with fruits that can contaminate harvest, such as black nightshade, the preharvest treatment can dessicate the foliage but will not affect the fruits, except that dessication of weeds may result in fruits closer to the soil.

Preharvest treatments are not intended to be used to speed up crop maturity, and largely do not accomplish this.  The restrictions on preharvest treatments that specify how mature the crop must be at time of application are designed to minimize any effect of herbicides on crop maturation.  Applying earlier than specified could interfere with that process.  The residue tolerances for this use are also based on a certain application timing, and failure to follow label guidelines could result in illegal herbicide residues in grain.  For crops being grown for seed, and for sweet corn and popcorn, be sure to check with the seed company/processor for approval prior to using any preharvest treatments.

Thinking about storing more grain this fall?

Source: Chris Bruynis, OSU Extension

There are several market factors that may have farmers looking to increase their storage for this fall. With lower prices, some farmers will look to store grain and hope prices will improve. With the current basis and price improvement between the harvest period compared to the January/March delivery period of 22 to 40 cents for corn and 16 to 34 cents for soybeans, elevators are sending a message to store grain.

The concern I have is that we will use some facilities that are not typically used for grain storage making aeration challenging at best. With poor air movement, grain going into storage will need to be of better quality, lower foreign material, and probably lower moisture.

Farmers interested in learning some strategies for successful drying and storage of grain, specifically corn and soybeans, are invited to join a Zoom Webinar on Monday August 24, 2020 at 8:00 PM.  Dr. Kenneth Hellevang, Ph.D., PE, Extension Engineer and Professor from North Dakota State University will be the featured speaker. He is one of the leading experts on grain drying, handling and storage.

To join the webinar, go to https://osu.zoom.us/j/7911606448?pwd=L1pQQ0VoODROZG56Q015enNBQkVVUT09 and enter the Password: STORAGE

Also, if you cannot attend the program during the broadcast time, the recording will be available on the Ohio Ag Manager website following the program. The recording will be located at  https://u.osu.edu/ohioagmanager/resources.

If you have questions, fell free to contact Chris Bruynis, bruynis.1@osu.edu or 740-702-3200. If you need assistance logging in on the evening of the program, contact David Marrison at 740-722-6073 or marrison.2@osu.edu.

Iowa Farmers Face Harvest Challenge

Source: Todd Neeley, DTN

The derecho fizzled out before it reached us!  I remember the one several years ago, the damage can be amazing.  Iowa farmers were hit hard by a derecho this year.

 

OMAHA (DTN) — One thing has become clear as crop experts tour the damage left behind by the derecho that ripped through Iowa this week: Farmers will face a multitude of challenges come harvest.

Trevor Birchmier, a farmer and owner of Central Iowa Shortline of Maxwell, a farm store and equipment business, told DTN that about 2,400 acres of corn went down on his farm in addition to three 42-foot bins holding 40,000 bushels each.

In all, he lost a total of between 150,000 to 175,000 bushels storage.

Prior to the storm, his crop was doing well.

“We were looking incredible,” Birchmier said. “Barely got rain, but when it came, it was at the right time. Such a good spring and early part of the growing season. It got a great start. Our corn looked tremendous. We were looking forward to a heck of a bumper crop, probably one of our best.”

So far, Birchmier has bagged between 100,000 and 150,000 bushels, with hopes his bins can be repaired before harvest.

“We called our contractor,” he said. “He assured us we will have bins by harvest on concrete pads that are there. It seems far-fetched, but I hope it happens.”

For his customers, Birchmier said he ordered an extra 750,000 bushels of storage bags to help area producers.

Preliminary estimates place total damaged acres at around 10 million, with a wide variety of damage from field to field across central and eastern parts of Iowa.

That’s on top of millions of bushels of commercial and on-farm storage lost in winds topping 100 miles per hour in some areas of the state.

YIELD LOSS POTENTIAL

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Leafhoppers, Grasshoppers, and Beetles, Oh My!

Source: Kelley Tilmon, Andy Michel, OSU

As the summer progresses we are receiving reports of insect problems often encouraged by hot, dry weather.  Last week we reported on spider mites and especially if you are in an area of continued dry weather we recommend scouting your soybeans and corn  https://agcrops.osu.edu/newsletter/corn-newsletter/2020-22/watch-spider-mites-dry-areas .

Some areas are also reporting increases in young grasshoppers in soybeans, another insect favored by dry weather.  Grasshoppers of often start on field edges so early scouting may allow for an edge treatment.  Japanese beetles are another common defoliator of soybean that are starting to appear.  Both of these pests fall into a general defoliation measurement, and we recommend treatment if defoliation is approaching 20% on the majority of plants in post-flowering beans.  Download our guide to estimating defoliation in soybean at https://aginsects.osu.edu/sites/aginsects/files/imce/Leaf%20Defoliators%20PDF_0.pdf

A weird problem being reported not just in Ohio but in parts of the Midwest as far-flung as Minnesota is the red headed flea beetle, which is being found in corn and soybean.  This is a small, narrow, shiny black beetle with a red head which springs like a flea when disturbed.  Feeding in soybean creates small round holes and in corn longer narrow strips of damage.  This feeding is seldom economic.  In soybean follow the general defoliation threshold of 20%.  Leaf feeding in corn is almost never economic, but be on the watch for silk-clipping, which is rare but possible.  There are no thresholds in corn, but our Minnesota colleague Bruce Potter suggest this guideline: “flea beetles are very numerous (it is likely more than 5-10/plant), pollination is less than 50% complete, and numerous plants have silks clipped to within 1/2 inch, you might consider an insecticide.”

Finally, earlier in the season we reported higher than usual numbers of potato leafhopper in alfalfa and encouraged stepping up scouting.  In some fields third-cut alfalfa is being heavily impacted by this insect.  You can review our scouting advice for this insect at https://agcrops.osu.edu/newsletter/corn-newsletter/2020-17/time-start-scouting-potato-leafhoppers-alfalfa

Mid-Season Weed Management in Soybeans – Hot, Dry Edition

Source: Mark Loux, OSU

A few weed-related observations while we try to stay cool and hope for a day of rain or at least popup thunderstorms.

 

  • One of the frequent questions during extended dry weather is – do I wait for rain before applying POST herbicides, or just go ahead and apply before the weeds get any larger and tougher to control.  Our experience has been that it’s best to go ahead and apply when weeds are still small, even if it’s dry, and herbicides will usually do what they are supposed to.  Letting them get larger without any sure forecast for rain can make for a tough situation that requires higher rates or a more injurious mix.  On the other hand, waiting to apply can be fine if there is a good chance of rain within the next few days.  It’s not always an easy decision.
  • The deadline for applying dicamba to Xtend soybeans was June 30.  Tavium can still be applied where the soybeans were planted less than 45 days ago and have not exceeded V4, an alternative to dicamba will have to be used.  We should point out that very hot days and warm nights are not appropriate conditions for applying dicamba anyway.
  • The replacement for dicamba on Xtend soybeans is usually going to be glyphosate or a mix of glyphosate with either fomesafen (Flexstar, etc), Cobra/Phoenix, or Ultra Blazer.  Will they cause soybean injury?  Yes.  Will the injury be worse under hot conditions?  Probably.  Do you want weed control?  We assume yes.  Using a less aggressive adjuvant approach can reduce the injury.  Example – applying fomesafen with MSO + AMS will be less injurious than COC + UAN.  Be sure to use adjuvants appropriate for the weed species and size though.
  • Applying POST herbicides early or late in the day may have some potential to reduce injury.  Keep in mind however that the activity of most POST herbicides on weeds is reduced during overnight hours.  In previous OSU research where we applied herbicides at 3-hour intervals from 6 am to 9 pm, activity was substantially reduced from 9 pm through 6 am.  So activity was decreasing after 6 pm and ramping back up after 6 am.  Our studies included fomesafen, glyphosate, Firstrate, 2,4-D, and glufosinate.  Of these herbicides, 2,4-D was the only one not affected by time of day.   Giant ragweed was the only broadleaf weed in the 2,4-D study, which occurred in wheat stubble.

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Drought Projections Do Not Go Well With Fungicide Applications

Source: Anne Dorrance, Pierce Paul, OSU

Several calls this past week for fungicide applications on corn and soybean at all different growth stages.  So let’s review what might be at stake here.

Soybeans.  Frogeye leaf spot and white mold on susceptible varieties when the environment is favorable for disease easily pay the cost of application plus save yield losses.  Let’s dig a bit deeper.  Both of these diseases are caused by fungi but frogeye leaf spot is a polycyclic disease, meaning that multiple infections occur on new leaves through the season while white mold is monocyclic and the plant is really only susceptible during the flowering stage.  Both of these diseases are also limited geographically in the state.  White mold is favored in North East Ohio and down through the central region where fields are smaller and air flow can be an issue.  Frogeye has been found on highly susceptible varieties south of 70, but it is moving a bit north so it is one that I am watching.

White mold is also favored by closed canopy, cool nights and high relative humidity.  So farmers in these areas should double check their variety ratings first.  If it is moderate to low score for resistance (read the fine print) then this year a spray may be warranted.  We have gotten consistent control of white mold with Endura at R1.  Herbicides that are labeled for white mold suppression have also knocked back this disease, but if a drought occurs or no disease develops, losses of 10% or greater can occur due to the spray alone.  For these purposes R1 is a flower on the bottom of 1/3 of the plants in the field.

Frogeye leaf spot –There also must be some inoculum or low level of disease present in the field for this disease to cause substantial and measurable yield losses.   This disease will only move in the canopy when there is regular rainfall.  And again only on susceptible varieties. With dry weather, this will sit and hold. Time to scout for this will be at the end of flowering if it can be found in the field.  With drought conditions, the disease will not impact the crop.

The story is very similar from a corn pathology standpoint. Most of our major diseases (gray leaf spot, northern corn leaf blight, eye spot) are driven by wet, humid conditions, consequently, the dry weather we have experienced over the last several days will keep most diseases in check. Fungicides are not warranted under these conditions; it just does not pay. Although some product labels may mention yield responses under drought-like condition, our data do not support such a benefit. We see the highest yield responses when fungicides are applied to susceptible hybrids at VT-R1 under disease-favorable conditions. These conditions would include extended periods of dew and high relative humidity, especially during the early- to mid-morning hours.

For a disease like southern rust that usually blows up from the south, and tar spot, an emerging disease of increasing concern in the state, fields should be scouted before making an application. Both diseases develop well under warm conditions, but they also need moisture and high relative humidity to spread. In the case of tar spot, based on what we have seen in 2018 and 2019, it usually develops well into grain fill (R4-R5), and as such, may have little effect on grain yield. Data from some states in the western half of the corn belt show that when tar spot develops early, yield loss may be substantial. The same is true for early southern rust development. So, scout fields to see what is out there and at what level before investing in fungicide application.

Soybean Vegetative Growth Stages- VC vs V1

By: Laura Lindsay, OSU

Across the state, soybean growth and development is variable, ranging from early vegetative stages to flowering. However, there has been some confusion regarding the identification of the VC and V1 growth stages. This confusion is mostly due to two definitions of V1…that actually mean the same thing. The Fehr and Caviness Method (1977) is based on the number of nodes that have a fully developed leaf, whereas Pederson (2009) focuses more on leaf unrolling so that the leaf edges are no longer touching. The VC definition for both methods is the same, but the differences start to appear between the methods at V1. Fehr and Caviness define V1 as “fully developed leaves at unifoliolate nodes,” which also means that there is “one set of unfolded trifoliolate leaves unrolled sufficiently, so the leaf edges are not touching.” This second definition is common in extension publications (Pedersen, 2009).

Soybean growth stages are described in the OSU Corn, Soybean, Wheat, and Forages Field Guide (available for purchase here: https://extensionpubs.osu.edu/corn-soybean-wheat-and-forages-field-guide-pdf/). A visual guide to soybean staging is available as a pdf from Dr. Shawn Conley at the University of Wisconsin-Madison (https://coolbean.info/library/documents/2017_Soybean_GrowthDev_Guide_FINAL.pdf).