Under surveillance

Toward the end of the growing season, it can be easy for soybean growers to assume the only thing needed until harvest is favorable weather. Often, this thought occurs about the time the soybean plants canopy over the rows and weed control is all but ensured. However, MFA’s Crop-Trak consultants know that their work is just beginning.

Reproductive stages of soybean growth and development are called the critical period for a reason. Lost leaf area is tougher to replace than during vegetative stages. Aborted blooms will never develop into pods. Pods clipped by insects will not produce grain. Stress from any source can impact the size and quality of the grain. And, this is when foliar diseases will impact the crop the most.

Crop-Trak consultants continue thorough field surveillance before and during critical growth stages to ensure fungal disease pressure is kept in check. Depending on the disease, late-season pressure is something that can be mitigated by fungicide applications, but critical to success are early detection, proper identification and correct product selection. These three factors are the tenants of Crop-Trak’s disease control recommendations.

Early detection

Preventative treatments of fungicides are much more popular than they once were. Growers often see benefits in terms of yield and disease control when making a fungicide application at early pod set. This application is often made without intensive scouting to determine the presence of a disease, and even then, gains can be realized.

If yield benefits are often realized without scouting for the disease, why is thorough scouting so important? Because it is possible or even likely for many diseases to start showing up before the onset of pod development. By the time visible symptoms of a disease appear, the plant is already infected. The goal is to detect these symptoms when a small number of leaves are first infected and then treat to prevent further infection. Regardless of whether the fungicide is a “curative” or “preventative” type of fungicide, an application will only prevent further plant tissue damage, not repair damage that is already done. This is the reason for weekly Crop-Trak field inspections up to and all the way through critical reproductive periods. Diseases don’t always follow the calendar, and growers must be ready for an early arrival.

Product selection

Proper identification of soybean diseases not only helps determine whether a field should be sprayed, but also ensures the proper product is selected to remedy the problem. This is important because not all fungicides are the same. Most foliar-applied fungicides fall into one of three families or modes of actions: strobilurin, triazole and SDHI (succinate dehydrogenase inhibitor). All three families have strengths and weaknesses compared to the other two. As an example, strobilurins are excellent against many diseases, but they are ineffective against frogeye leaf spot in areas where it has developed resistance. That means two or three modes of action are preferable to fight resistance development.

Beyond using the correct family of fungicides, the specific product can be very important. For instance, only a limited number of products have activity on white mold, and they must be applied in a specific window.

Selecting the proper foliar fungicide and applying at the correct timing are not only good stewardship practices but also ensure that yield is protected. Even when growers have a planned late-season application, its success can only be ensured by intensive and timely scouting. Growers can expect just that from the weekly field visits provided by the Crop-Trak program.

Proper Disease ID

When it comes to identifying diseases in soybean fields, it’s important to know what diseases are problematic versus ones that have more limited yield impact. Because the differences from one disease to the next can be subtle, it often takes a trained eye to identify them. Crop-Trak’s consultants and agronomists have extensive experience developed by walking soybean fields every year. Their collective expertise provides the resources critical for proper disease identification and control. These pictures show several diseases broken into three categories:

Bacterial Diseases

These seldom have an economic impact on soybean yields. Even if the disease were severe enough to cause economic damage, there are few control options. Bacterial infections are much more commonly found after rain or irrigation. For example, disease can be spread by rain splashing bacteria onto plant tissue.

Large angular reddish brown lesions with yellow halos are indicative of bacterial blight.

Pale green spots with brown centers and a yellow halo are symptoms of bacterial pustule. Spots may contain a blister on the lower leaf surface.

Fungal Diseases of Minor Economic Importance

Though fungicides will have activity on most of these diseases, rarely are these issues of economic importance in Missouri and surrounding states. Making a fungicide application based solely on finding these diseases may be a mistake.

When Asian Soybean Rust first arrived in North America, it was a disease of great concern, but the threat never materialized. This disease prefers tropical environments like those in parts of South America, where it is a very devastating disease. Easily confused with bacterial diseases, ASR lesions lack the yellow halos but contain small, volcano-like pustules.

Downy mildew is a common sight in soybeans. The upper leaf surface will exhibit yellow spots while the corresponding underside will have small, cotton-like growths. The disease can impact seed quality but is rarely of economic importance.

An extremely common disease of soybeans, septoria generally only infects the lower canopy where small brown lesions will develop and can progress and run together. Infected leaves tend to drop prematurely, but economic returns for treating septoria alone are uncommon since the disease usually remains in the lower canopy.

Fungal Diseases of Significant Economic Importance

Proper identification of these diseases and quick response with appropriate control measures such as foliar fungicides will pay dividends for growers. Preventative measures or treating at the first sign of disease is vital to get the highest economic return.

Appearing first in the upper canopy, cercospora leaf blight gives the leaf a leathery, purple appearance. Cercospora may also lead to a condition in seed known as purple seed stain.

One of the most important diseases in terms of economic importance, frogeye leaf spot is a frequent concern to Midwestern soybean growers. It appears on leaves as grey lesions with a red border. In southeast Missouri and throughout the Delta, frogeye is known to be resistant to strobilurin fungicides, making product selection important.

While uncommon in Missouri, white mold is the most damaging late-season soybean disease in other parts of the Midwest. It is indicated first by white growth on infected stems, followed by development of black, hard fungal bodies and leaf death.

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Residuals help fight resistance

For years, we’ve waited for the Roundup Ready 2 Xtend trait for soybeans and the herbicide to use over the top. With EPA approval of dicamba-tolerant chemistry late last year, we are finally going to see what this technology brings to the table this growing season.

Stacked with both dicamba and glyphosate herbicide tolerance, the Xtend platform gives growers benefits not only on the genetics side but on the weed control side as well. The technology offers the yield and quality potential of Roundup Ready 2 soybeans with additional tools to control tough weeds such as waterhemp, marestail, giant ragweed, and Palmer amaranth, just to name a few.

Since last season, XtendiMax with VaporGrip and Engenia herbicides have both been labeled for use in Xtend soybeans. These are advanced formulations of dicamba with reduced volatility. New tank-mix products and nozzles have also been approved for use with the Xtend dicamba-tolerant crops.

We will still need to use tank-mix partners such as Authority, Sonic, or Valor. Diversifying your weed control program with different modes of action can preserve the effectiveness of the new seed traits as well as the new herbicide products designed to work with them.

The best strategy for any technology—Xtend, Roundup Ready, Enlist or Liberty Link—is overlapping residuals. This is the use of a full rate of a pre-emerge herbicide applied at planting followed with a post-emerge application of another residual 20 to 30 days later. The second residual should be applied and activated by rain before time expires on the first herbicide activity. The goal is to never let weeds out of the ground.

I believe the greatest benefit of this system will be in the burndown market. You can make a burndown application with dicamba and residual and have no plant-back restrictions. However, this won’t be the glyphosate system you have been accustomed to. This technology will provide a benefit only if you use it right. We have heard about all the risk associated with dicamba. If we make sure we are following the proper guidelines, I believe we can use these products successfully.

During my meeting schedule over the winter, I had the opportunity talk internally to my fellow MFA employees as well as producers about the advantages and challenges of dicamba-tolerant crops. I generally tried to scare folks to the ledge, and then walk them back. I would always end my discussion by saying, “Don’t be scared of it.” We must be diligent and cautious of this system, but I want growers to benefit from the technology without being constantly scared. That’s when we tend to make mistakes. Unfortunately, with dicamba, we’ve learned mistakes can be costly. Compared to glyphosate, it takes such a small amount of dicamba to show damage in an off-target crop. The sensitivity to non-tolerant plants is unlike anything we’ve dealt with before.

No matter what weed control program you are using on your farm, I hope it is successful. But don’t forget where we’ve come from. Weed resistance has been here for a long time, and it’s not going away any time soon.

If you have questions or would like to develop sound weed control options, see your local MFA Agri Services or AGChoice location.

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Soybean seed care goes beyond the surface

Control of early-season soybean diseases, at the surface, can seem very simplistic. Just glancing at the seed to see if its beige color has been traded for a flashier red, green, blue or pink may be all a grower needs to be assured of protection against soybean diseases.

Truth is, control is much more complex than that.

At one time, regardless of the seed brand, it was likely that the treatment was the same—or at least very similar. Now, the number of different seed treatments is almost as diverse as the number of brands of seed on the market. This is both a blessing and a curse. With interest in seed treatment has come innovation and new products but also deception. This is particularly true with tightened margins. Many seed dealers are offering a cheaper option that may have active ingredients that do not control the total spectrum of soybean diseases, or rates have been reduced to ineffective levels.

Often these changes are dictated by a seed company, and an ingredient change may have been made while the product name remained the same. There are times when a seed company will not release the rates of active ingredients a seed treatment product contains. Though a seed treatment product label must state the concentration of active ingredients, that does not mean it is a legal requirement on the seed tag. The best thing growers can do to protect themselves is to make sure to ask questions about what treatment is being applied to the seed.

Among the first questions to ask a seed provider is to produce a label for the seed treatment. Second, confirm the rate of application. Knowing the product ingredients and rate is of utmost importance to determine if the product actually provides sufficient control of the four main early-season soybean diseases: phytopthora, pythium, rhizoctonia and fusarium. These economically damaging diseases can kill and rot seeds before germination or cause seedling death. Many products available today may not contain the diversity of ingredients needed for adequate control of all four.

At other times, particularly when it comes to phytopthora, product use rates may not be adequate for disease control. In addition to learning about the effectiveness of control for the four main seedling diseases, the product label and rate will give insight about whether the treatment contains an insecticide or whether it may provide control of other diseases such as soybean cyst nematode or sudden death syndrome. SCN and SDS are two of the most damaging pathogens to soybean production. Often, control of these two soil-borne diseases will come from a second product tank-mixed at the dealer’s treater.

Thankfully most of the changes in the seed care industry have been advancements, but growers need to remain wary of deceptive marketing and cut rates in the name of cost cutting. Seed care is no different than weed control. The most expensive application is the one that is ineffective. A good place to start when seeking information is your MFA agronomy specialist, who can help ensure your seed-care plan is successful for your operation.

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'New era' for N Management

Last year, MFA took on a major field study to evaluate sidedress application of nitrogen on corn and some new nitrogen rate decision tools. Now that the results are in, I have been speaking about it regularly at many of our training meetings. Whenever I bring up the topic of sidedressing—especially when I talk about waiting until plants are knee-high to do it—a murmur starts somewhere in the back of the room and sweeps forward. I see people shifting nervously in their seats, anxious about the big “what if?” What if I don’t get the N on in time? What if the corn gets too tall? What if I stress the corn by waiting that long to sidedress?

Even with the big “what ifs,” our 2016 study gives us a big reason to re-evaluate the way we manage N for our corn crop.

The amount of N we need to raise a corn crop varies tremendously from year to year and from one end of the field to the other. In my presentations, I refer to a couple of university studies that show variations of 100 pounds per acre in rates needed for optimum yield. In early July, if you were to walk through fields that have a flat rate of 160 pounds of nitrogen applied, you’d likely find sections showing nitrogen stress that probably never had the potential to yield 140 bushels per acre. You’d see other areas that are dark green and beautiful that will end up yielding 200-plus bushels per acre.

Why do we have such variations? Really, it comes down to two things: water and soil. Nitrogen loss is controlled by the amount and timing of the water we receive from the time N is applied until corn takes it up. Soil properties control how much N our organic matter will provide and the predominant pathways for N loss. Rainfall fluctuates from year to year and drives our overall N rate variation, while the soil affects the in-field variability.

In the past, it has been difficult to quantify and predict these changes, so we’ve used the “better safe than sorry” rule. Based on local conditions and experience, we’ve learned that if we apply “X” amount of nitrogen (insert your favorite rate here), everything will be OK. This works great 80 percent of the time. We have plenty of N, and we make a good crop. However, that also means many years we apply more N than we really needed, and sometimes we run out of N at a critical time and yields suffer.

Research and development into N management is starting to pay off. Today, several services are available to better define our N needs. During the 2016 season, MFA compared three different nitrogen management tools (NVisionAg, Climate FieldView Pro and Adapt-N) head-to-head on 1,700 acres across our trade territory. The results were surprising. Overall these tools performed admirably well, with yield differences among all the programs and the check strip falling well within the margin of error.

All three programs recommended N rates much lower than I was comfortable with, but I was astonished at the results. One field made 240 bushels per acre on a 160-pound average N rate. But we must consider that many areas had almost perfect conditions for nitrogen last year. Early-season weather was warm and dry, which encouraged mineralization and minimized losses. Then we had moisture late in the season when the crop needed it. Overall the tools we tested were able to recognize the low N need, and when we applied accordingly, we were able to see a significant savings in our N costs.

I don’t expect those savings every year. In fact, we’re more likely to make money with the programs by improving our yields when we have a wet spring and have seen large N losses.

However, there is a catch with these programs. They all work better the farther we get into the season because water plays such a big part in determining how much N we need. The more we know about the seasonal rainfall pattern, the better the tools can predict what we need in post application. In last year’s study, we targeted corn at the V8 growth stage for sidedress application, which put us right at the edge of rapid plant uptake of N.

We also have to leave room for the tools to save us money, which means using low rates in pre-emergent applications. In our trials, we applied no more than 100 pounds of N before sidedress. This can lead to a tense June if weather conditions don’t allow for sidedressing, but high-clearance spreaders and airplanes are available in many areas to help extend the season.

Is it worth the risk? I think there are opportunities to save money and increase yield with these tools. With their performance last year, I am convinced we are on the brink of a new era for N management.

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New crop technologies trigger new policies

As the meeting season begins to slow down and the busy spring season gears up, I hope you’ve learned a few things that will impact your operation in a positive way. If you are a row-crop producer, I’m sure you have been informed about the do’s and don’ts with new herbicide technology—specifically, dicamba—that may be coming to your field or a neighboring farm.

When the subject has come up at meetings over the past six months, I’ve often heard someone say, “We’ve been through this before, and we did just fine.” I hope that that’s the case this time as well. However, compared to glyphosate, it takes such a small amount of off-target dicamba to cause visible damage to crops. Only milliliters of dicamba in a 1,000-gallon tank can cause problems.

With everything going on in the industry today related to this new technology, I want to share MFA’s policy about dicamba:

  • MFA will not custom apply any old formulation of straight dicamba products (including Banvel, Clarity and Detonate). 
  • MFA will not sell over-the-counter any old formulation of straight dicamba products (including Banvel, Clarity and Detonate) between April 1 and Oct. 1 each year. These products will be available outside this timeframe.
  • This policy does not include blended products such as Range Star, DiFlexx and Status.

What does that mean? MFA will steward the new technology to the best of our ability. We will apply and sell new-and-improved formulations, and we will use them as labeled. We believe that this policy is the best for your cooperative. We have heard about all the risk associated with dicamba, and we want to make sure we are following the proper guidelines. I believe we can use these products successfully.

MFA will also participate in the Flag the Technology (see above), a program that the University of Arkansas started several years ago to identify what crop technology is in each field. MFA will provide black-and-white checkered flags with your MorSoy RXT soybeans. We ask that you place these flags in the RXT fields to not only remind you what is planted in that field but also to make your neighbors aware. This will hopefully avoid misapplication of chemicals or drift on your field. MFA personnel are not responsible for placing the flags in the field; you are.

In the past few years, we have seen an increase of LibertyLink fields in our territory, which has caused some issues with spraying the wrong herbicide on the wrong trait. You can guess the outcome. That’s why MFA is taking extra measures to avoid any confusion with the Xtend system. If we will be custom applying XtendiMax or Engenia to your fields, we ask that you communicate with your location in writing via email, text or written document stating what technology you are using. Simply bring in your planting maps, and denote what herbicide trait is in each field. If these documents are correct, and we make a mistake, it is our fault, and we will make it right. Communication among your neighbors, retailer and the applicator is crucial to success.

I’ve had some producers tell me they don’t think this policy will work. I’ve had some even ask me, “Why are we planting Xtend soybeans?” Well, they’re a tool—a great tool, in fact—that allows growers to utilize XtendiMax or Engenia in a burndown situation and plant without the typical plant-back restrictions. It also provides a weapon against weeds that escape our residuals if they are less than 4 inches tall.

With all that being said, we cannot forget the journey that led us here: resistance in the 1990s, glyphosate resistance in the 2000s, HPPD resistance and PPO resistance. It’s only a matter of time until we have resistance to new technologies as well. They aren’t like Roundup Ready. We won’t be able to kill pigweed 2 feet tall. For that matter, anything over 4 inches tall is questionable. We must continue to use residuals and overlapping residuals as I have written about in the past. I’ve heard a lot of chatter about abandoning residuals. This is a big mistake! If we abandon what we have learned, we will be right back where we came from.

If you have any questions, please feel free to reach out to your MFA or AGChoice location or to me directly at This email address is being protected from spambots. You need JavaScript enabled to view it..

Hear Dr. Weirich speak about MFA's new policies regarding dicamba:


 Also, learn more about the flag system in the MFA Agronomy Guide here:


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