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Looming threats, leading players

GROWERS SHOULD BE ON THE LOOKOUT for two emerging corn diseases in MFA territory—tar spot and bacterial leaf streak—according to Dr. Kaitlyn Bissonnette, University of Missouri plant pathologist.

“Tar spot been found in four northeastern Missouri counties: Lewis, Clark, Scotland and Marion,” she said. “With tar spot, you can see about 30 to 40% yield loss in hard-hit areas. This is an emerging disease, so we haven’t seen those levels, but we need to be monitoring it because as it moves, that potential for yield loss increases.”

Tar spot can be found anywhere on the corn plant, but often is found in the lower canopy from mid-to-late August through harvest. It can be identified by its stromata, which are fungal structures that appear as small, raised, black, circular spots.

Bacterial leaf streak (BLS) has been found in Ray and Chari­ton counties in Missouri and often resembles gray leaf spot, Bissonnette said. BLS often infects leaves after strong winds and rains have caused leaves to rub together. To identify this particular disease, growers should look for water soaking and long, necrotic lesions with irregular margins, she said.

Growers are asked to contact their local MU Extension office or Bissonnette at This email address is being protected from spambots. You need JavaScript enabled to view it. if they detect either of these diseases in their fields.

Though not considered emerging diseases, gray leaf spot, southern rust and northern corn leaf blight should also be top-of-mind for producers, Bissonnette said.

“Those are usually the main players we usually think about in corn,” she said.

In soybeans, she encourages growers and scouts to watch for frogeye leaf spot, cercospora leaf blight, sudden death syn­drome and soybean cyst nematode. Target spot is also a concern in soybeans and cotton for some parts of the state.

In wheat, growers should look for fusarium head blight and stripe rust, though the latter depends on the season.

“Stripe rust requires a living host to survive because it’s an obligate parasite,” Bissonnette said. “It doesn’t overwinter in residues, so that means that it has to stay alive in places like Louisiana or Arkansas, and then it’ll blow into our area.”

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Help your crop win the arms race for survival

DISEASE. It seems like the topic is all around us these days. But what farmers and researchers alike know is that it doesn’t just seem like disease is everywhere. It is everywhere.

The thought can be overwhelming, and because these organisms are often out of sight, it’s also easy to ignore their existence. But Dr. Kaitlyn Bissonnette, assistant Extension professor in plant sciences at the Uni­versity of Missouri in Columbia, spends a lot of time at the microscope looking at infected plants and knows the impact of diseases can’t be dis­counted.

“Disease will always be present at some level. It’s just about minimiz­ing the amount,” said Bissonnette, a third-generation plant patholo­gist. “When we’re talking about plants, disease literally blows in the wind. It overwinters on plant residue and in soils.”

What’s more, she said healthy plants make for healthy hosts, creating an “arms race for survival.”

“When we think about healthy plants with high nitrogen, those plants tend to actually be more susceptible to disease,” Bissonnette said. “Because as much as plants like nitrogen, so do fungi. While we’re trying to create as much yield as we can per acre, we’re also feeding the pathogens. They’re trying to grow and survive as much as the plant is trying to grow and survive.”

When it comes to controlling disease, it all comes down to manage­ment, she added. And it starts with knowing the land and its history.

R.G. Kirby, who farms 750 acres in Fayette, Mo., understands the importance of managing his crops closely for disease and other threats to their performance. In fact, he relies on Charlie Ebbesmeyer, MFA Crop-Trak consultant and local agronomist, to be another set of eyes in the field. Ebbesmeyer has an advantage here. He grew up just a couple of miles down the road and began working on Kirby’s farm at the age of 14 during the summer. Kirby also participates in MFA’s Nutri-Track program, and Ebbesmeyer helps with that soil sampling.

“We’re patch farmers,” Kirby said. “We farm a patch here and a patch there, but Charlie knows these fields. I don’t have to tell him how to get around.”

Ebbesmeyer not only knows where each field is, he knows how it’s been managed. Kirby’s operation is largely no-till. While the practice has made a positive difference in the soil organic matter, Ebbesmeyer knows disease can persist on those residues, creating additional need for disease deterrence.

Kirby often interseeds clover hay into wheat or uses wheat as a cover crop in rotation with soybeans. Thanks in part to his Crop-Trak consultant’s watchful scouting, last year Kirby harvested some of the best wheat he’d ever seen. But the season didn’t start that way. Early on, Ebbesmeyer found evidence of fusariam head blight in the crop and brought it to Kirby’s attention.

“I started to see small amounts scattered throughout his fields,” Ebbesmeyer said. “With the wet spring we had last year, I knew it was a good possibility for this disease to have damaging effects on his crop.

We went in with a timely application of the full rate of Miravis Ace (fungicide), and I didn’t see any issues grow past what was already there. I looked at a few other fields in the area, not on R.G.’s farm, that didn’t receive a fungicide, and they were hit hard with head blight. Because of this, along with his incredible yields last summer, we know that the fungicide application was the right call for his farm.”

Kirby and his wife, Marilyn, are both retired schoolteachers who have always farmed in addition to their previous full-time employment. The couple has participated in MFA’s Crop-Trak program for the past 10 years.

“It’s an important part of our operation. We don’t use any chemicals unless Charlie tells me to in his scouting report,” Kirby said. “I see those reports every week, usually the day he’s out here.”

Now in their 70s, the Kirbys have started the process of tran­sitioning the farm to the next generation. They have two daugh­ters, one who lives in Kansas City and another who lives in South Carolina. Crop-Trak has provided the added benefit of helping them understand what’s happening on the farm from a distance.

“With computers and phones, and the eventual help of a farm manager, they’ll be able to continue to run this,” Kirby said. “They ask questions based on the scouting report. I also share it with the sharecroppers we work with and our financial institu­tion, so they know what we’re doing out here, too. They all have a vested interest in our farm.”

START WITH THE SEED

Environmental factors and certain cultural practices can de­crease disease risk, Bissonnette said, but the best protection is seed selection.

“Disease management, first and foremost, is about un­derstanding when to plant a resistant hybrid or variety,” she said. “Most farmers have an idea of field history, especially for obvious diseases such as sudden death syndrome or sometimes soybean cyst nematode, if they’ve done sampling recently.”

But, she emphasized, some of the more subtle diseases, such as frogeye leaf spot or gray leaf spot, may be harder to recognize just driving by the field.

“The best resistance is genetic resistance, so that’s where we start,” said MFA MorSoy Product Manager Tommy Lee, who gathers information on disease tolerance from both breeder data and MFA’s own field observations. “If a grower has a problem with sudden death year after year, he could use a seed treatment to help with that issue. But seed treatments are chemical, so it’s eventually going to break down and wash out of the root zone, leaving the plant susceptible. So, starting with good genetic tolerance and then building upon that is the way to go.”

It’s an age-old tale—resistance—a tug-of-war between the plant and pathogen. Every species is programmed to survive and overcome. But through science, humans have intervened, using plant breeding as a way to give the crop an advantage.

“With plants, there are some types of resistance in which a single gene will work on a particular pathogen,” Bissonnette said. “But nowadays, we often see multiple genes acting on a specific pathogen, which results in more durability, less ‘failure in the field,’ if you will, and less chance of the pathogen over­coming that resistance. That’s why knowing what diseases are in certain fields and using that information for variety or hybrid selection is the first line of defense.”

Crop rotation and proper row spacing are among the factors that play a key role in mitigating disease pressure. Conversely, irrigated crops may suffer increased risk due to many fungal pathogens’ propensity for damp conditions.

“It really depends upon the disease,” Bissonnette said. “Open­ing up the rows and increasing air flow in the canopy can help with many diseases. There are others that favor certain crop rotations. For instance, tar spot tends to show up in continuous corn production, and in the Bootheel region of our state, target spot occurs in both cotton and soybeans.”

Target spot isn’t the only disease to cross species, she said. The pathogen of fusarium head blight infects both corn and wheat, while charcoal rot exists in both corn and soybeans.

“Southern blight also has something akin to 200 host spe­cies,” the plant pathologist said. “That’s mostly in horti­cultural production, and not so much in field crops, but we occasionally see it. Rotation is definitely one of the things you have to consider when planning for the next season.”

BACTERIAL? VIRAL? FUNGAL? PARASITE? NONE OF THE ABOVE?

Pathogens take many forms, but more than 75% are fungal. Some require a living host and will only sur­vive for a single season in Missouri, while others may be structured for much longer lifespans outside their plant hosts.

Identifying diseases often takes a trained eye. Signs and symptoms may overlap or resemble other agro­nomic issues like herbicide injury, and often multiple diseases may be present at once.

“Rarely do I walk into a field and only see one dis­ease,” Bissonnette said. “If the environment is condu­cive for one disease, it’s usually conducive for many. Diseases are opportunistic. Once a plant becomes stressed, it can open up the avenue for other infections to move in.”

Because pathogens can be transmitted by different types of organisms, knowing what’s present in the field affects how it can be treated. And, with fungicide resis­tance on the rise, that knowledge is more critical than ever, Bissonnette warned. When fungicide is necessary, proper management is about using multiple modes of action and really understanding when to spray.

“If it’s a bacterial or viral pathogen, don’t spray a fungicide,” she said. “Like herbicide resistance man­agement, the more we expose a pathogen to fungicide, the more likely resistance is to develop.”

For fungicide application, timing is key, emphasizes MFA District Agronomist Shannon McClintock. It was the sole focus of the presentation he gave at MFA’s an­nual Training Camp, held virtually this year. In that pre­sentation, he laid out the specific application windows for common diseases in soybeans, corn and wheat.

On Kirby’s farm, Ebbesmeyer knew the window was brief for treating the fusarium head blight.

“You don’t have a lot of time when dealing with wheat,” he said. “Depending upon the season, weather and chemical, you can have anywhere from as long as a week to as little as two days.”

That quick turnaround is just another factor in the Crop-Trak equation, Kirby said.

“It’s the prime reason he [Ebbesmeyer] is out here,” he said. “It’s of paramount importance that we get timely applications. He’s tied to that spray rig, too, so when he sees something, he’s able to make a phone call and get someone out here.”

Bacterial diseases are a different ballgame, Bisson­nette said. When it comes to the control of these pathogens, there’s little to be done outside of cultural control methods such as row spacing and residue management to decrease the bacteria present in the fields, she explained.

Additionally, while viral diseases can and do show up in Missouri fields, she said most usually don’t pose a significant threat to yield.

“Viral organisms are most often transmitted through insects, so management of those pathogens is more about insect control,” Bissonnette added. “There are not a lot of viral diseases that I am concerned about, and most of them don’t cause significant yield loss.”

Nematodes often get lumped in with diseases, but they’re actually a pest that causes disease. Much of Bissonnette’s recent research centers around soybean cyst nematodes, tiny parasitic roundworms that are one of the largest contributors to yield loss in soybeans. These nema­todes work their way into the root of a plant and establish a feeding site, leaving a cyst on the root itself. Once established, it leaches water and nutrients from the plant, causing the plant stress.

Bissonnette said there are even pathogens that fall outside these catego­ries that are neither fungus, bacteria, virus nor parasite.

“They’re called oomycete pathogens,” Bissonnette said. “Things like pythium and phytophthora are considered fungal-like organisms, and we control those with specific seed treatments. There are no foliar applica­tions that can be made for those.”

Again, Bissonnette stresses that a field’s history can help predict the field’s future.

“What it comes down to is if you don’t have your field history, it’s really hard to implement effective man­agement practices,” she said. “Getting out into the field, scouting and knowing what’s going on helps you to have a better feel for what types of yields you might see and what your potential can be for years to come.”

It can be a balancing act to produce a profitable crop while fighting against factors such as diseases that are seemingly beyond control, but MFA has the products, services and expertise to help producers maintain and regain that balance. For more information, contact your MFA Agri Services or AGChoice location or visit https://mfa-inc.com/PrecisionAg/Crop-Trak.

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MFA's 2020 crop trials provide valuable data for decisions, even without in-person trainings

Every year comes with challenges, and 2020 was certainly no exception. Much of what we do in MFA’s Agronomy Division was put on hold or altered because of COVID-19. Every year, our agronomists and product managers put together extensive trials that range from compari­sons of corn and soybean varieties to applications of fertilizer, fungicide and everything in between. This research allows our team to get first looks and evaluate products to provide solid agronomic information for MFA employees and producers. This gives everyone confidence in the products we recommend or use, because we know they have been proven in the field.

While COVID-19 concerns didn’t stop that important trial work, it did make it more challenging to conduct the in-person training we always hold for our employees and producers. We had to adjust. We hosted smaller group tours and produced training videos. Our annual MFA Training Camp was held virtually so employees could still see, hear and learn about our trials.

Though certainly not ideal, the situation provided insight about how technology now allows for digital training and information-sharing. But, let’s be honest, virtual presentations can’t replace in-person interaction in which you can physically see the products, ask questions and have conversations. We hope tours and trainings can resume in 2021.

In 2020, we conducted trials at two training sites. Our main location is in the Missouri River bottoms outside Boonville, Mo., where we have 20 acres split in a corn-soybean rotation. We’ve conducted trials there for nine years. Our second site, which we’ve used for the past two years, is east of Columbia and consists of 35 acres of corn and soybeans. There, we have designated six of those acres as corn-on-corn and plan to gain more data for this type of rotation.

These training sites give our agronomy team a hands-on approach to testing and product evaluation. As you will see in the results, this time we focused on fungicides and foliar nutritionals. We also conducted va­riety trials for MorCorn, MorSoy, DeKalb, Asgrow, Brevant and NK seeds along with seed treatments, fertilizers and seeding populations for corn and soybeans.

Beyond these two training sites, MFA also conducts numerous replicated and large-scale on-farm trials across our trade territo­ry. In 2020, we had 79 such trials evaluating foliar nutritionals, fungicides, fertilizers and anhydrous ammonia stabilizers. On the following pages are summaries of some of these trials and results of our agronomic research.

CORN HYBRID TRIALS

The MorCorn trials at both our Columbia and Boonville lo­cations were planted on April 20 with a population of 32,500 plants per acre. We tested the same varieties for each trial at both sites. A total of 59 varieties were tested ranging from 104-day relative maturity to 118 days. We tested 11 MorCorn com­mercial checks against 21 experimental varieties and 27 other varieties split among DeKalb, Brevant and NK hybrids. Due to data agreements, the information we can share in this article will be only for the MorCorn varieties and experimentals.

The plot site in Boonville was fertilized with 300 pounds of actual nitrogen in the form of SuperU the day after planting. The plot site in Columbia, however, did not receive nitrogen until the corn was around V5 growth stage, when we applied 180 pounds of SuperU. Even with the late application, we were still able to produce a good corn crop because corn doesn’t use most of its nitrogen until the V6 growth stage.

This demonstrates the importance of getting nitrogen on the field at the right rate and time but also ensuring that it is protected by nitrogen stabilizers to reduce loss before the plant uses it.

Most of our trade territory had a great growing season, and our plot yields show it. At the Boonville site, the top end hit 283 bushels per acre with a couple of experimental varieties, while the low number was an experimental variety at 239 bush­els per acre. In Columbia, the top end hit 262 bushels per acre with an experimental variety, while the lower end was MorCorn 3544 at 212 bushels per acre. Results can be seen in Fig. 1A, 1B and 1C. In addition to our training sites, these hybrids were tested across multiple environments and geographies in 12 oth­er locations within MFA’s trade territory. Fig. 1D shows a yield comparison for hybrids tested multiple times from 2015-2020 at these replicated sites.

SOYBEAN VARIETY TRIALS

The diversity in the MorSoy lineup reflects the diversity in MFA’s trade territory. The portfolio includes soybean matur­ities from 3.6 to 4.9 and seed traits such as LibertyLink, Enlist E3 and Roundup Ready Xtend. We were even able to test some experimental lines of soybeans with the Roundup Ready XtendFlex trait, which was introduced by Bayer this past year. Fortunately, XtendFlex technology was fully approved in August 2020, allowing us to harvest those plots and collect yield data.

The MorSoy variety trial in Boonville was planted on June 3, but we had to replant the early-maturity group 3 beans on June 16. Since XtendFlex soybeans were a stewarded product going into the 2020 planting season, we weren’t able to plant those varieties at this site because it had flooded in the past five years. The Columbia site was planted on June 1, but heavy rains caused poor emergence, and all trials there were replanted on June 17. The population was 140,000 plants per acre.

Overall, we tested 69 varieties including 28 MorSoy commer­cial checks against 17 experimental varieties and 24 additional varieties split among Asgrow, Brevant and NK brands. As with the corn data, we will only be sharing the MorSoy products and experimentals per our data agreements.

The soybean varieties were broken into four trials by relative maturity ranges. The trials include all of the herbicide technol­ogy traits combined, so weed control was maintained with a sound agronomic conventional herbicide program. Results can be seen in Fig. 2A, 2B, 2C and 2D. In addition, these varieties were tested across multiple environments and geographies in 12 other locations. In Fig. 2E, you can see a yield comparison for our commercial varieties tested in 2020 across those sites.

FUNGICIDE TRIALS

Over the years, benefits from foliar fungicides have been well documented, both from a disease control standpoint and positive effects on plant growth and development. Last year at our Columbia site, we began to look at the impact of fungicide by variety. We continued this study in 2020 by doubling the replications of corn and soybean trials. We applied fungicide in the VT-R1 timeframe for corn and R2-R3 timeframe for soy­beans. Fig. 3A, 3B, 3C and 3D show the combined yield for all of the soybean varieties for the untreated block and the block treated with Miravis Top. We realized a 4- to 10-bushel increase on the plots treated with fungicide. The tables for corn are not presented, but we saw an increase of 6 to 8 bushels.

FUNGICIDE TIMING

Continuing our focus on fungicides, we wanted to look at the best timing for application. In our trials, we applied fungicide on corn and soybeans at seven different timings, two at early vegetation stages and five during each of the early reproductive stages. The data shown is a combination of the three trials we have completed in the past two years. As you can see in Fig. 4A, for corn there is a statistically significant advantage to applying fungicide from VT to R2. Soybeans didn’t show a statistically significant difference, but there was trend toward higher yield advantage in the earlier reproductive stages (R1-R3).

SLOW-RELEASE NITROGEN & FOLIAR NUTRITION TRIALS

We have seen the benefits of fungicide, but is there a way to boost the fungicide to provide an even better return? Slow-release nitrogen (SRN) gives us that opportunity by working synergistically with fungicides, most importantly those with strobilurins. SRNs provide an efficient method of delivering low-use rates of nitrogen to the plant when it is being stressed, resulting in more gains at higher N efficiency. MFA’s own Gold Advantage Trend-B is an SRN with added boron, an essential nutrient needed during a crop’s reproductive stages for grain development. However, boron is not very mobile within the plant. When taken up early, boron likely won’t move enough to the areas where the plant most needs it. By applying Trend-B, we are not only providing nitrogen to help the fungicide in­crease plant performance, but we are also helping to provide optimal boron nutrition.

Proper timing is crucial to get the most out of SRNs and fungicides. We have done many studies with Gold Advantage Trend-B as well as fungicides paired with Gold Advantage Corn and Soybean foliar nutrition. The results have been positive. 

This past year in a large-scale farm trial, we saw an increase of 10-plus bushels per acre from a fungicide application. The field was also split with an application of fungicide with Trend-B, which resulted in an additional 4 bushels per acre.

Foliar nutritionals are by no means a way to replace sound soil fertility, but they can enhance the plant’s ability to use readily available nutrients at peak uptake to help produce a top crop.

ARRESTED EAR

While fungicides can pay large dividends, there can be some drawbacks if not used properly. When looking at when and what fungicides to apply, we shouldn’t overlook the importance of using the right adjuvant. Adjuvants are used in almost all tank-mix combinations to improve the efficacy of the pesticides, such as ammonium sulfate (AMS) with glyphosate.

The three main types of adjuvants on most pesticide labels are non-ionic surfactant (NIS), methylated seed oil (MSO) and crop oil concentrate (COC). Each has its own unique properties to improve the efficacy of pesticides. In general terms, NIS products are considered spreaders and help the spray particle to cover more of the leaf surface. MSOs and COCs are oil-based products, allowing for better penetration of the waxy cuticle on the plant’s leaves while also providing additional spreading of the spray droplet.

Most fungicide labels for corn recommend the use of an adjuvant during application—usually an NIS, especially in late applications that likely will be applied by airplane. However, the labels usually caution applicators not to use the fungicide with an adjuvant between the stages of V8 and prior to VT. Use of an adjuvant during these growth stages may stress the plant and inhibit kernel develop­ment, resulting in an arrested ear.

In this year’s crop trials, we looked at the impact of using an adjuvant with the fungicide, Trivapro, at the V14 timeframe in corn. We compared treatment of an untreated check, fungicide only and fungicide with MFA’s adjuvants Astute (NIS), Soy Plus (MSO) and Xpond (high surfactant oil concentrate). The data in Fig. 5A is just from the Boonville site, but we saw the same trends at each location. Compared to the untreated check, all of the treatments with fungicide provided some yield benefit at both application timings. However, in this data set there is a 15-bushel decrease when applying fungicide with NIS prior to VT as compared to application at the VT-R1 time­frame. We saw 3% to 4% arrested ear development in the treatments that included NIS at V14. By having the NIS with fungicide at the proper timing (VT-R1), there was an increase in yield when compared to fungicide only.

This trial emphasized the importance of understanding the growth stage of your crops to help avoid any unneces­sary side effects of applying pesticides or additives at the wrong time.

POPULATION TRIALS

We often get questions about soybean populations and what is considered a viable stand to determine replants. For the past two years, we have conducted trials to determine the impact of plant population on overall yield. Fig. 6A shows yield results from three trials as well as the combined average. The overall results show that planting at least 140,000 plants per acre pro­vides a yield increase compared to lower planting populations. The same trend is true in each individual trial result. Observa­tions of these plots indicated that lower populations actually promoted weed pressure because canopy closure was more difficult.

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