Pesticides

New Enlist Labels – When Enlist is Outlawed, Only Outlaws……

By: Dr. Mark  Loux, OSU Extension

Sometimes you’d like the s**t to stop hitting the fan just long enough to get cleaned up, but you can’t get a break. Like when you’re in the middle of an endless pandemic, a worldwide shipping fiasco, herbic ide scarcities and price increases, and parts shortages. And just when you had it worked out to use Enlist herbicides on Enlist soybeans for 2022 so you wouldn’t have to deal with dicamba, their use is no longer legal in your county. We’re trying to find something reassuring to say here, but there’s not much.  The USEPA issued a new seven-year registration for Enlist One and Enlist Duo, valid through January 2029.  Changes include a revised application cutoff for soybeans, “through R1” that replaces “up to R2” on previous labels, and the addition of  a slew of spray nozzles to the approved nozzle list.  The most significant change for Ohio is that due to changes in Endangered Species information, Enlist One and Enlist Duo cannot be used in 12 Ohio counties:  Athens, Butler, Fairfield, Guernsey, Hamilton, Hocking, Morgan, Muskingum, Noble, Perry, Vinton, and Washington. We contacted Corteva to see if this was likely to change anytime soon, and got no assurances of this, although the PR information they have distributed indicates it is possible.

This really couldn’t happen at a worse time for growers in these counties. We lack solid information on herbicide availability and price, and it’s a fluid situation, but it appears that glyphosate and glufosinate can be in short supply, and prices high.  Glyphosate resistance in key weed species makes us dependent on POST soybean herbicide systems based on use of glufosinate (Liberty etc), dicamba (XtendiMax/Engenia), or 2,4-D (Enlist One/Duo). The Enlist system allows use of glyphosate, glufosinate, and 2,4-D, and combinations of these.  While Enlist soybeans are tolerant of other 2,4-D products, Enlist One and Duo are the approved 2,4-D products for all POST applications to Enlist soybeans, and any preplant or preemergence applications that occur less than 7 days before planting or anytime after planting.  As far as we know, this prohibition of use does not apply to legal uses of other 2,4-D products.  Some things to consider here:

– Some growers/applicators were planning on omitting glyphosate from burndown and/or POST applications.  In the Enlist system, this increases the overall importance of the 2,4-D in these applications.  Where the Enlist products cannot be used, revaluation of the mixture is warranted.  It may be necessary to use glyphosate, or an alternative 2,4-D product in the burndown (with a 7-day wait to plant), or other herbicides, such as Sharpen or Gramoxone.

– The most obvious replacement for Enlist products in POST applications is glufosinate since glyphosate won’t control most populations of ragweed, waterhemp, or marestail.  Growers going this route should check on availability and price immediately, since supply seems to be finite.  For those in the 12 counties who are unwilling or unable to use glufosinate, the Enlist soybean essentially becomes a RoundupReady soybean with respect to herbicide use.

– Most users of glufosinate supplement the grass control by including either glyphosate, or a POST grass herbicide such as clethodim.  Glufosinate is weak on barnyardgrass and yellow foxtail, volunteer corn, and large grasses in general.

– While spray volume and nozzle type are not that critical for effectiveness of 2,4-D and glyphosate, glufosinate requires these to be optimized to maximize activity.  Most growers tell us that for glufosinate, 20 gpa works better than lower spray volumes.  The nozzles that work well to minimize off-target movement of Enlist products may not be optimum for glufosinate.

– Where 2,4-D cannot be used in the POST, the effectiveness of the residual herbicides used becomes more important.  Glufosinate applied alone or with just a grass herbicide can be less effective on certain broadleaf species, and large weeds in general, compared with mixtures of 2,4-D with glufosinate or glyphosate.  We recommend using residual herbicides at planting, and possibly increasing herbicide rates and the overall complexity of the mixture.

Information we have received from Corteva includes several documents with explanation of label changes and restrictions, and supplemental labels for Enlist One and Enlist Duo.  Aside from this, we don’t know any more than anyone else.

Save the Dates – Central Ohio Agronomy School

Due to COVID uncertainties the 2022 Central Ohio Agronomy School has been pushed to March. 

Monday March 7 – 6:30 – 9:00p.m.

Monday March 14 – 6:30 – 9:00p.m.

Monday March 21 – 6:30 – 9:00p.m.

Monday March 28 – 6:30 – 9:00p.m.

The School will be at the new Ramser 4-H Activity Center (on the fairgrounds)

700 Perimeter Dr.  Mount Vernon, OH  43050

More details to come

Cressleaf Groundsel (Packera glabella)

Source: Marcelo Zimmer and Bill Johnson, Purdue University

Every spring we receive several calls and e-mails about a certain 3-foot tall weed with yellow flowers (Figure 1). The most common yellow flowered weeds we have in Indiana are cressleaf groundsel, the buttercup species, and dandelion.  Occasionally we have some fields of canola or rapeseed in the state. But, by far the most prevalent specie we see in no-till corn and soybean fields, and occasionally pastures, is cressleaf groundsel.  I have only rarely observed wild mustard in Indiana.  Wild mustard is more common in the northern tier of states near the Canadian border.  This year, due to recent cooler weather, cressleaf groundsel is flowering later than it did last year.  This article is intended to provide information on the biology and life cycle of cressleaf groundsel, as well as how to control it in fields and pastures.

Biology and Identification

Cressleaf Groundsel is a winter annual weed that has become more prevalent in Indiana pastures and agronomic crop ground over the past 20 years.  The small seeds produced by this weed allow it to thrive in reduced and no-till systems as well as poorly established pastures.  Cool and wet springs of the past few years have also favored cressleaf groundsel, as it is a weed that prefers moist soils and typically struggles in hot and dry weather.

Much like most winter annual weeds, cressleaf groundsel emerges as a rosette in the fall then bolts, flowers, and produces seed in the spring.  Basal rosette leaves are deep pinnate serrations with roundly lobed leaf margins.  Leaves are typically 2 to 10 inches in length (Britton and Brown 1970).  Bolting stems are hollow and can reach up to three feet in height with inflorescences that contain six to twelve yellow ray flowers that are often compared to the flowers of common dandelion.  When looking for cressleaf groundsel in older weed id or taxonomic guides be aware that it has traditionally been placed in the Senecio genus and only recently was placed into the Packera genus.

Toxic Properties

The competitiveness of cressleaf groundsel with agronomic crops has not been researched, though its presence as a winter annual in no-till fields will have the same implications of slowing soil warming and drying as other winter annual weeds.  The presence of this weed in pastures and hay fields should be of more concern as it does contain toxic properties when ingested by livestock.  Leaves, flowers, and seeds of cressleaf groundsel contain alkaloids that will cause liver damage in livestock that is termed seneciosis and typically occurs on a chronic level (Kingsbury 1964).  Symptoms of seneciosis are loss of appetite, sluggish depressed behavioral patterns, and in extreme cases aimless walking without regard to fences or structures.  Although cressleaf groundsel is not as toxic as many of its relatives in the Packera genus, livestock producers encountering this weed in pastures or hay should take steps to avoid prolonged ingestion by animals.

Control

Herbicide applications for control of cressleaf groundsel are most effective when applied to plants in the rosette stage.  Plants that are larger, or bolting are very difficult to control with herbicides.  Infestations in pastures can be controlled with 2,4-D or a combination of 2,4-D and dicamba applied to rosettes in the fall or early spring prior to bolting.  Producers should be aware that applications of these herbicides will also kill favorable broadleaves (legumes) that are present in pastures.

Control recommendations for cressleaf groundsel in no-till agronomic crop fields has typically been to apply 2,4-D @ 1 qt/A to actively growing rosettes in the fall.  In fact, just about any broadleaf herbicide commonly applied in the fall in the eastern cornbelt will work well on controlling this weed.  However, we have observed that control of cressleaf groundsel with spring burndowns can be challenging if the plants are large and spray applications are made in cool weather.  In situations like this, we often observe severe injury and necrosis of leaves, but new growth will appear from live buds on the plant.  In some instances, resprays are needed to finish off the cressleaf groundsel. The best herbicide programs for spring burndowns are 2,4-D + dicamba, atrazine + paraquat + 2,4-D, something with chlorimuron in it, and Elevore + 2,4-D. for more information on spring burndown information, consult the burndown section in the Weed Control Guide for Ohio, Indiana, and Illinois (publication WS-16).

 

Adapting Burndown Programs to Late-Planted Situations

Source: Mark Loux, OSU Extension

It’s déjà vu all over again.  We have run this article every few years, and it seems like maybe the frequency is increasing as we deal with wet and cold weather that delays planting.  The questions about this have not changed much, and neither have the suggestions we provide here.  One of the most common questions, predictably, is how to kill glyphosate-resistant marestail and giant ragweed and generally big weeds in soybeans when it’s not possible to delay planting long enough to use 2,4-D ester (Enlist soybeans excluded since there is no wait to plant).  Overwintered marestail plants become tougher to kill in May, so this is an issue primarily in fields not treated last fall.  The good news is that we have more effective herbicide/trait options for help with burndown compared with a few years ago.  The bad news is that nothing we suggest here is going to be infallible on large marestail.

A burndown of glyphosate and 2,4-D struggles to control marestail in the spring anyway, especially in the absence of fall herbicide treatments.  Our standard recommendation, regardless of when spring treatments are applied, is to either replace the 2,4-D with something more effective, or to add another herbicide to supplement the 2,4-D.  Sharpen has been the frequent replacement/supplement, and we now have the option to use dicamba in the Xtend soybean system instead of 2,4-D.  While it’s possible to use higher 2,4-D rates in the Enlist soybean without waiting to plant, higher rates do not necessarily solve this issue based on our research, although a follow up POST treatment that includes glufosinate or 2,4-D usually finishes off plants that survive burndown.  There’s a list of suitable soybean burndown treatments in our marestail fact sheet, and also below – these are for fields not treated the prior fall.

  • Glyphosate + saflufenacil + 2,4-D (+ metribuzin if possible)
  • Gramoxone (3-4 pt) + 2,4-D + metribuzin
  • Glyphosate + dicamba (Xtend soybeans)
  • Glyphosate + dicamba + saflufenacil (Xtend soybeans)
  • Glufosinate + Sharpen (+ metribuzin if possible)

Salfufenacil herbicides include Sharpen, Zidua PRO, and Verdict.  It is possible to use a mix of glyphosate, saflufenacil, and metribuzin, omitting the 2,4-D, but control can be more variable.  We have observed some weakness also with the glyphosate/saflufenacil combination on dandelion, purple deadnettle, and larger giant ragweed.  There is usually going to be a benefit to keeping 2,4-D in the burndown where possible, as part of a more comprehensive mixture.  We advise against using Gramoxone unless it can be mixed with both 2,4-D and a metribuzin-containing herbicide.  One strategy would be to plant corn first as soon fields are fit, and delay soybean planting so that 2,4-D could still be used.  And a reminder – deciding to include saflufenacil at the last minute can result in a need to alter the residual herbicide program.   Labels allow mixtures of Sharpen/Verdict with herbicides that contain flumioxazin (Valor), sulfentrazone (Authority), or fomesafen (Reflex) only if applied 2 or more weeks before planting.

Some other things to consider in a delayed burndown situation:

1.  Aside from glyphosate-resistant weeds, increasing glyphosate rates may be one of the most effective ways to maintain effective control.  We suggest a rate of at least 1.5 lb ae/A, and higher rates could be warranted.  This will not improve marestail control, but should help with most other weeds, especially under (presumably) warmer May conditions. Continue reading →

Take Care When Washing Work Clothes Used Around Pesticides

Source: Elizabeth Danielson, ISU Extension

Pesticide applicators and handlers need to wear, at a minimum, the Personal Protective Equipment (PPE) specified on pesticide product labels. Most pesticide labels require a long-sleeved shirt and long pants. Proper laundering of work clothes that may be contaminated with pesticide residues is essential to reduce pesticide handlers’ short- and long-term exposure to pesticides and prevent the potential of residue cross-contamination onto other clothing.

Many pesticide labels provide limited instructions for cleaning work clothes. In situations where no instructions are provided, the following are guidelines for caring for and laundering pesticide contaminated clothing. A downloadable publication, Laundering Pesticide-contaminated Work Clothes, provides additional, more detailed information.

 

Roundup vs. Roundup vs. Roundup – REALLY??!

 

From a consumer standpoint this could quite possibly be the worst product marketing of ALL TIME!

 

 

Roundup has been around for a long time.  The active ingredient in “Roundup” is glyphosate.  Many of us know “Roundup” as a non-selective herbicide – i.e. it will kill all plants it contacts.

So what’s the problem?  With these products having a similar name, it’s quite possible to grab the wrong product from the shelf and thus risk harming or destroying the wrong (or all) plants.

The Solution.  Always read the label!  Products with similar names may have different active ingredients and therefore may not have the have the desired outcome.

Below is a general guide to the different Roundup products available to consumers.  Note that for many of these products there may be ready to use (RTU) and/or concentrate formulations available with different ratios or percentages of the same active ingredients.  Additional products are marketed for use in southern turfgrass.

Don’t be fooled by products that have a similar name . . . read the label!

 

Calibration for Rate Controlled Sprayers

Source: Erdal Ozkan, OSU Extension

I had an article in last week’s CORN newsletter encouraging growers to fine tune and calibrate their sprayers. I had mentioned that the next couple of weeks may be the last best time period to do this since planting season is just about to start. There would not be any better time to do this than now. The next day I got an email from a grower asking me this question that I get often: “I have a rate controller in the cab that regulates the flow rate of the sprayer regardless of the changes in sprayer ground speed. So, should I still calibrate the sprayer to find out the application rate?”. The answer is, Yes, you should. Although the rate controllers do an excellent job with regulating the flow rate of nozzles to keep the application rate constant, a manual calibration at least once a year is needed to ensure the rate controller is functioning properly.

Here is why we should confirm the accuracy of rate controllers: Unfortunately, electronic controllers usually cannot detect flow rate changes on each nozzle on the boom, and none can detect changes in spray pattern. If a nozzle is plugged, or extremely worn out, the rate controller cannot tell us this is happening. It will still try to maintain the constant application rate by changing the system pressure and force other nozzles to spray less or more to overcome the problem in one or several nozzles. If the ground speed sensor works based on revolutions of the tractor wheels, the ground speed determined may not be accurate, because of the slippage that may occur under some ground conditions. Even the tire pressure being off just a few psi may change the tire revolutions per minute leading to erroneous travel speed readings. Finally, Controllers don’t show changes in spray patterns that may happen when a nozzle is defective, plugged, or worn-out. So, we will have to continue manually checking the flow rate of the nozzles, and visually observing the changes in spray patterns until the technology is developed to do these observations remotely, and on-the-go.

As I mentioned in the article in last week’s CORN newsletter, it usually doesn’t take more than 30 minutes to calibrate a sprayer, and only three things are needed: a watch or smart phone to record the time when measuring the nozzle flow rate or the travel speed, a measuring tape, and a jar graduated in ounces. Please take a look at the Ohio State University Extension publication FABE-520 for an easy method to calibrate a boom-type sprayer.  Here is the URL for this publication: http:// ohioline.osu.edu/factsheet/fabe-520  

Not knowing limitations of rate controllers may create serious problems. I already mentioned how smoothly the rate controllers keep the application rate the same regardless of changes in travel speed. However, this convenience comes at a cost if the controller is forced to make drastic changes in the application rate as a result of too high or too low of a travel speed. As you know, to achieve best results from pesticides, the application rate, as well as the droplet size must remain relatively unchanged during the entire spraying. When sprayer speed goes up, to maintain the pre-set application rate, the controller requires the system pressure to go up to increase the nozzle flow rate. This, unfortunately results in more drift-prone droplets coming out of the nozzle, especially if the nozzle used is designed for low application rates within the recommended pressure ranges. Conversely, when the sprayer slows down, the opposite happens: the controller forces the system to lower the pressure, in order to reduce flow rate of nozzles. This will result in production of larger than the desired size of droplets, leading to inadequate coverage. If you are spraying Dicamba or 2,4-D herbicides, you need to pay even more attention to operation of rate controllers. As you know, only a small number of nozzles at specific ranges of pressure can be used to spray these products. Significant changes in ground speed may force the rate controller to make significant changes in spray pressure that may be outside the allowable legal pressure range required to spray these herbicides. Without you realizing it, you may find yourself in violation of the label. Make sure the nozzle size selected will allow the controllers to make necessary changes in the flow rates while still staying within a safe, applicable and allowable pressure range.

Now is the Time to Fine Tune Your Sprayer

Source: Erdal Ozkan, OSU Extension

Pesticides need to be applied accurately and uniformly. Too little pesticide results in poor pest control and reduced yields, while too much injures the crop, wastes chemicals and money, and increases the risk of polluting the environment. Achieving satisfactory results from pesticides depends heavily on five major factors:

  1. Positive identification of the pest.
  2. Choosing the least persistent and lowest toxicity pesticide that will work.
  3. Selecting the right equipment, particularly the right type and size of nozzle for the job.
  4. Applying pesticides accurately at the right time.
  5. Calibrating and maintaining equipment to make sure the amount recommended on the chemical label is applied.

Inspection of sprayers

Higher pesticide costs and new chemicals designed to be used in lower doses make accurate application more important than ever. There is no better time than early spring to take a closer look at your sprayer. Here are some of the things I would recommend you do this week if you don’t want to unexpectantly halt your spraying later in the season when you cannot afford delaying spraying and missing that most critical time to control weeds:

  • First, if you need new or one other type of nozzles on the boom this year, do not delay purchasing new nozzles. Do it now.
  • Double-check your sprayer for mechanical problems before you start using it.  You won’t have time to do this when planting is in full swing.
  • Clean the sprayer tank thoroughly and make sure all filters on the sprayer, especially the nozzle filters are clean.
  • Clean spray nozzles to make sure they are not partially plugged. Check their flow rates, and replace the ones that are spraying more than 10 percent of the original output at a given spray pressure.
  • Check the agitator in the tank to make sure it’s working properly. This is extremely important if you will be applying dry chemicals. Run water through the spray system to make sure everything is working properly.
  • Always carry a spare, excellent quality pressure gage (glycerin filled) in your shop, and check the accuracy of the pressure gage on the sprayer compared to the reading you see on this spare pressure gage. Your rate controller will not know if your pressure gage is bad, and the flow rate of nozzles will be adjusted by the rate controller using the bad pressure gage.
  • Once you are convinced that all sprayer parts are functioning properly, it is time to calibrate the sprayer.

Calibrate the sprayer

One can determine if the chemicals are applied at the proper rate (gallons per acre) only by carefully calibrating the sprayer. Calibration, perhaps more than anything else, will have a direct impact on achieving effective pest control and the cost of crop production. While applying too little pesticide may result in ineffective pest control, too much pesticide wastes money, may damage the crop and increases the potential risk of contaminating ground water and environment. Results of “Sprayer Calibration Clinics” I participated in Ohio a while back, and data from several other States show that only one out of three to four applicators are applying chemicals at a rate that is within 5 % (plus or minus) of their intended rate (an accuracy level recommended by USDA and EPA). For example, if your intended rate is 20 gallons per acre, the 5% tolerable difference will be 1 gallon (5% of 20). So, your actual application rate should be as close to 20 gpa as possible, but not outside the range of 19 to 21 gpa.

How do you calibrate the sprayer?

There are several ways to calibrate a sprayer. Regardless of which method you choose, you will end up measuring the nozzle flow rate (in ounces), and the actual travel speed in miles per hour to determine the actual chemical applied in gallons per acre. Once you determine the actual application rate, you should find out if the difference between the actual rate and the intended rate is greater than 5% of the intended rate (plus or minus). If the error is greater than the 5% tolerable error margin, you will need to reduce the error below 5% by doing one of three things: 1) Change the spraying pressure, 2) change the travel speed, and 3) change nozzles (get a different size) if the error cannot be reduced below 5% by making adjustments in either the pressure or the travel speed, or both.

It usually doesn’t take more than 30 minutes to calibrate a sprayer, and only three things are needed: a watch or smart phone to record the time when measuring the nozzle flow rate or the travel speed, a measuring tape, and a jar graduated in ounces. Please take a look at the Ohio State University Extension publication FABE-520 for an easy method for calibrating a field crop (with boom) sprayer.  Here is the URL for this publication: http://ohioline.osu.edu/factsheet/fabe-520