Will crop rotation still protect against corn rootworm?

Written by Jason Worthington on .

 When discussing insect management with growers, the preferred strategy of management is often a “wait and see” approach. Waiting until insects are found before deciding on a management practice can be effective for some species, if a field is scouted thoroughly and frequently enough. However, this same practice falls woefully short on other species, especially when managing insects that could cause devastating yield losses or pose a predictable threat to a crop. Corn rootworm falls into both these categories.

The most damaging corn pest in North America, corn rootworm pressure is documented almost every year at some level in areas that are in a continuous corn rotation. Over the past two centuries, Missouri corn growers, unless they were in a corn-on-corn rotation, didn’t have to worry much about corn rootworm pressure. That may be about to change.

Crop rotation traditionally controls rootworm. That’s why there has been limited concern in our area about corn rootworm pressure. Beetle eggs would hatch in the spring, but if the larvae did not find a food source (corn), they would quickly perish. The vast majority of Missouri’s corn acres are in a corn/soybean rotation, so growers were putting an insect management plan in place with their crop rotations.

However, in July 2016, MFA Crop-Trak Consultant Kevin Moore discovered the likely presence of northern corn rootworm extended diapause, a longer life cycle in which the eggs remain dormant in the soil for two years or more before hatching. Evidence of larvae and adult beetles were found in numerous corn fields in a corn/soybean rotation in Atchison, Nodaway, Holt and Worth counties in Missouri as well as Page County, Iowa. Many other parts of the U.S. already experience extended diapause rootworm and cannot count on crop rotation for control any longer.

To confirm these findings, MFA partnered with the USDA to conduct lab testing of suspect beetle populations. In these tests, eggs from collected beetles endured a simulated winter. A typical diapause, or period before eggs hatch, is one winter. In an extended diapause, rootworm eggs must endure two or more winters before hatching. After the first winter and spring of testing populations collected from northwest Missouri, only 45 percent of the eggs hatched. While it is unknown what portion of the remaining 55 percent will hatch after a second winter, it is likely a significant number of these eggs are still viable and could threaten a corn crop. At 45-percent hatch after one winter, the numbers closely resemble testing of known extended diapause rootworm populations in South Dakota.

What does this mean for growers in these areas? First, the threat could be much greater in 2018 because it’s an even number year like 2016, when the extended diapause was discovered. Methods other than crop rotation must be used to control rootworm. The most effective plans must be proactively developed along with hybrid selection.

When it comes to managing rootworm, reactive control measures will not be effective. The two real options a grower has to control rootworm are Bt corn traits with multiple effective proteins such as SmartStax, and granular in-furrow soil insecticides such as Force or Aztec. Both of these control options require planning ahead. With few planters in the state set up for dry insecticide applications, traited seed will likely be the preferred method of control. The decision to purchase seed with rootworm control traits often happens before the prior year’s harvest is even complete.

While rootworm can be devastating to a crop and extended diapause situations may keep crop rotation from protecting us, we still have options to control this pest. Just like many of our most important decisions, we will have to plan ahead to ensure success against this emerging threat.

Clear Choice

Written by Allison Jenkins on .

 Statistics vary, but it can take hundreds to thousands of years to form an inch of topsoil—something that will never happen again in our lifetime or many generations to come. That’s why erosion control was a big factor in Davis’ decision to begin growing cover crops five years ago on his farm in Mexico, Mo.

When more than 9 inches of rain fell the last weekend of April this year, Davis realized just how well his cover crop of cereal ryegrass was working compared to fields without it.

“I had just planted a field of corn near my house, and at the end of the driveway the water flowing out of that field was just completely dirty,” Davis said. “The field of ryegrass next to it? The water running out of it was just as clear as can be. It didn’t have all that sediment and soil because the cover crop was holding it in.”

From an initial 20 acres of cover crops, Davis has now increased that number to around 200 acres out of the 1,200 he farms in total. The cover crops on his farm all precede soybeans.

“There’s no doubt cover crops are making a difference,” he added. “The soil I lose out of these fields, I’ll never get back. We have to do something to save it. I’d like to leave this farm better than what it was. Trying to do what’s good for the soil is one thing I can accomplish.”

He’s not alone in the quest to control erosion and reap other benefits of cover crops. An increasing number of growers across MFA country are embracing this practice in which normally fallow ground is planted between seasons. The cover crop is harvested, grazed or terminated in the spring before the cash crop is planted.

In Missouri alone, recent surveys indicate 600,000 to 700,000 acres of cover crops or possibly more, compared to 400,000 acres reported in the 2012 Census of Agriculture.

“We’ve seen a rapid adoption of cover crops in the area served by MFA, mainly due to erosion and water quality issues, and I think that trend will continue,” said Dr. Jason Weirich, MFA Incorporated director of agronomy. “We have a lot of rolling fields and steep hills in our geography, and we see erosion and ditches washed out every year. With cover crops, we’ve seen a reduction in soil loss. They’re very successful when used properly.” 

Though cover crops offer numerous other advantages, erosion control is also the top priority for Ben Anderson, who farms 1,000 acres near Boonville, Mo., with his father-in-law, Perk Hoecker. Anderson moved from Kansas to the farm with his wife, Julie, five years ago to help her father transition into retirement. The family’s hillside farm has been in continuous no-till for about 24 years, and cover crops have been an integral part of the operation for the last decade. All of their corn and soybeans now follow cover crops.

“For years, we saw a lot of our creeks running muddy, and we’d have huge washouts,” Anderson said. “This farm sits on rich glacial deposit dirt, and we got tired of seeing it go down the creek. We’ve been trying to keep that dirt here, and now our creeks are running clear. We get good water retention, too, which is huge for us in-season.”

“It’s not for everybody, but with rolling hills like ours, it’s a pretty sustainable practice,” added Anderson. “They aren’t making any more dirt, so we want to keep what’s here.”

With the loss of soil comes loss of nutrients, so controlling erosion also protects a grower’s fertilizer investment. “Any time we have water movement, yield potential is leaving that field along with the soil and nutrients,” Weirich said.

In Missouri and surrounding states, cereal rye is by far the most popular choice in cover crops, Weirich said. Both Davis and Anderson exclusively planted cereal rye this year. Other viable options for our region include triticale, wheat, radishes, turnips, oats, buckwheat, crimson clover or a mixture of several species. Italian ryegrass, however, is not recommended, Weirich warned.

“Italian ryegrass is in the Lolium family, which is the No. 1 species in the world for herbicide resistance,” he explained. “It makes a great cover crop, but it has too many risks. You don’t have any control options once it establishes and becomes resistant to herbicides.”

Along with erosion control, Davis said cover crops have helped with weed suppression and cooler soil temperatures in the heat of summer, and he expects to find improved soil health and organic matter when he samples his fields this fall. Plus, he’s seen a yield boost every year.

“Last year we planted into cover crops that were waist high,” he said. “All the beans did really good last year, and I thought there’s no way the cover crop beans could be that much better, but they were. Those beans were a good 4 to 5 bushels better than anything else we had.”

Yield increases were also reported by a majority of respondents in the 2016 Cover Crop Survey conducted by the USDA’s Sustainable Agriculture Research and Education Agency, Conservation Technology Information Center and the American Seed Trade Association. The fourth annual survey of 2,020 respondents, including a significant number from producers in MFA territory, showed modest yield gains in both corn (1.9 percent) and soybeans (2.8 percent) following the use of cover crops. Cereal rye was reported to boost soybean yields on a majority of farms, and 82 percent of those surveyed indicated that cereal rye also helped reduce weed problems—including troublesome herbicide-resistant weeds. 

Establishing cover crops can be accomplished in several ways—typically drilling after harvest or aerial seeding into a standing crop—depending on the timing of planting and type of seed, Weirich said. Termination timing in the spring is also critical, he added, to ensure the cover crop doesn’t hinder the progress of the cash crop to follow.

“I know a lot of guys follow their combine with a drill to plant cereal rye, and that works well,” he said. “If you want to have a tillage radish or turnip, you need to overseed that into the crop. The key is making sure you get good fall growth. The more fall growth you get, the better off you’ll be by the time you terminate the crop in the spring.”

Weirich said there’s no way to make blanket recommendations for cover crops because every situation is unique. He recommends the Midwest Cover Crop Council’s website. Available at, the site features interactive tools that allow growers to make decisions at the county level based on the cash crop, planting and harvest date, drainage and goals.

“You have to make decisions based on your farm and what you want to accomplish,” Weirich said. “There are a lot of different options out there, so you need to know what you’re doing. It takes management the first several years. Don’t start with the whole farm. Figure out what works for you and your farm and then go from there.”

Nutrients now, flexibility later

Written by Kerri Lotven on .

 In the southern parts of MFA’s territory, producers like Billy Gourley of Gourley Land and Cattle in Ozark, Mo., are starting to think about the phosphorus and potassium levels in their fields. Split applications are popular here. By applying P and K in the fall and nitrogen in the spring, farmers in this area are able to spread out their resources, promote root growth in their pastures and ready their fields for the next season.

“When you fall fertilize,” Gourley said, “I believe you get more root growth, and your plant is healthier when it goes into dormancy through the winter. In the fall, you need that little bit of growth that comes with applying P and K because you can stockpile your grass and winter your cows without feeding as much hay.”

Gourley has about 2,000 acres of pasture enrolled in MFA’s Nutri-Track program and spreads P and K in the fall to winterize his pastures. He moved back to Ozark five years ago from Colorado to manage his family’s land. The pastures had been leased for the previous four years and needed a major overhaul. A few years ago, he attended a meeting where MFA personnel introduced grid-sampling.

“There were weeds everywhere, very little grass, no clover, no orchard grass,” Gourley said. “It was grazed to nothing. We came in with MFA and have done extensive amounts of renovation in our pastures. We’re not overgrazing. By grid-sampling and following proper soil-sampling and fertilizer programs, we’ve made leaps and bounds.”

Originally, Gourley wanted to hay his pastures. His plan was to fertilize in the spring, bale them once a year for hay, and then move in his cows to graze the rest of the time.

“When a bale is worth $22-25 and it costs $17-18 to put it up, the profit margin is not where it needs to be to make any money at haying,” he said. “I’m better off to buy my hay and graze my grass.”

In working with MFA, Gourley came up with another solution. He wanted to set up an intensive rotational grazing schedule that would give his cattle the ability to graze into early winter, allowing him to feed less hay. In the winter of 2015-16, Gourley supplemented grazing with more than 1,000 round bales, but in the winter of 2016-17, he was able to cut that number by more than half.

“Better management has just made our grass go further,” Gourley said. “We actually have over twice as many head now as we did in 2015 and 2016.” 

Splitting fertilizer applications between fall and spring has paid off for many producers in this area, according to Brandon Hebbert, who manages the MFA fertilizer plant in Ozark.

“P and K are not going to be mobile in your soil in the same way nitrogen is,” Hebbert explained. “So if you put it out in the fall and there’s any deficiencies, you’ve got all winter for those nutrients to start to break down and become available to the plant.”

While his location primarily applies P and K on pastures in the fall, Hebbert said some of the row-crop farmers in his area are seeing a benefit as well.

“We don’t have a lot of row crops around here, but some of the dairies have a few smaller fields,” he said. “In a lot of situations, the fertility is pretty low and they’re trying to get the most out of their yields. It takes a lot of fertilizer. By applying P and K in the fall, it helps stretch out resources for the farmer.” 

Post-harvest applications of fertilizer can also give row-crop farmers flexibility when their planting window is limited, he continued.

“Like I said, most of the guys who grow corn around here are dairy farmers, so they’ve already got a lot of their time spoken for,” Hebbert said. “Sometimes, having that P and K out there already can be the difference between getting a crop in or not.”

Brian Swadner, MFA’s precision specialist for the Ozark and Neosho area, said splitting applications of N, P and K not only aids plant health and gives producers better results, but it also allows MFA applicators to fill customers’ needs in the spring more efficiently.

“We want to be able to get out there and get the spreading and fertilizing done when the grower wants it,” Swadner said. “What we’ve been doing when we spread P and K in the fall kind of breaks up the normal schedule. When springtime hits, the stores are pretty busy spreading fertilizer. The variable-rate applications in the fall definitely help us to be able to provide the service to the customer when they want it.”

And, Hebbert added, it gives producers a little edge.

 “During green-up in the spring, we’re just a step ahead,” he said. “The producers who do this already have some of their starter fertilizer out there by splitting it before they put their nitrogen down. It just allows them to get a jump start and better yield overall.”

Improving pasture management on his family’s land has helped Gourley to grow the herd exponentially. He started with 16 heifers and a bull five years ago. The herd now numbers more than 900 head of cattle total. His ultimate goal is to be able to add 300-400 more head and run one cow per every two acres without supplementing his grass with feed.

“If you fertilize right, I believe your grass is going to grow. It should also have more nutrients which, in turn, should transfer to your cattle,” Gourley said. “Since we’ve started on the Nutri-
Track program, we’ve been able to run more head of cattle on less mineral, using less fertilizer because we have our soil in shape. I think that should be where everybody starts.”

For more information on the Nutri-Track program or fall fertilization, contact your local MFA Agri Services or AGChoice location. 

Pay close attention to applications

Written by Dr. Jason Weirich on .

This spring was another for the record books, and despite excessive rainfall, we are still off to a decent start in most of our trade territory. As we hit mid-season, here are some best practices to follow with crop protection applications:

Herbicide application

We were able to get our MorCorn replicated trials planted in perfect timing for the rain we had the last of April to the first of May. At our Training Camp site outside Boonville, emergence was six days after planting and reached V3 eight days later. It’s important to pay attention to making proper post-emergence applications. Just because the plant is 4 inches tall doesn’t tell you anything about how far along it is physiologically. Make sure you look at how many collars or trifoliates are fully emerged when making applications. Applying a herbicide after the specified growth stage can have adverse effects.

Cover crop termination

Spending several days on the road in April, I noticed something a little different than last year. A high percentage of the fields with cover crops established had been terminated prior to planting. The weather for this practice was more in our favor this year than in the past. However, I did receive several calls about poor product performance on terminating cover crops. Which product to use? What rate? What residual? When I took the calls, I asked a series of questions about herbicide applications and performance. Then I asked about the weather. If the grower made applications with the same mix on two different days and got different results, I followed by asking about high and low temperatures around the time of applications. In most cases, it seems that poorly controlled cereal rye is related to a cold spell at night or during the day. That would typically jog the grower’s memory, and then I would hear, “Yeah, it was 45 the day we sprayed it.” In some circumstances this may work, but when trying to terminate a dense stand, you need to make sure conditions are right for your application.

Adjuvant attention

The last thing I want to discuss is adjuvants. Adjuvants play an important role in your herbicide, fungicide and insecticide applications. Often, when we are making applications toward the end of the growing season, we tend to hear, “just leave out the adjuvant.” Most of the time, it’s about the checkbook—not any agronomic reason. However, I want you to think about the performance of the pesticide you are applying. When the pesticide label recommends a COC (crop oil concentrate), MSO (methylated seed oil) or NIS (nonionic surfactant), then it has a purpose. Most of the time it helps pesticides penetrate the leaf cuticle of the target weed or crop. This helps improve the performance of the product you are applying.

You’ve probably heard this statement before, but not all adjuvants are created equal. I get calls every year about dish soap, laundry detergent or something similar that producers would like to use as a surfactant. Our MFA Crop Advantage lineup is top notch. Ken Carmack, MFA adjuvant specialist, spends countless hours making sure that the best products are in our jugs. I know for a fact that our products aren’t always the cheapest on the market, but I can tell you they are some of the best. I can also assure you that they have been tested and validated to exceed expectations of performance.

If you have questions, feel free to contact one of our locations or email This email address is being protected from spambots. You need JavaScript enabled to view it..

Under surveillance

Written by Jason Worthington on .

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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