Growing Knowledge

Read the latest insights from our experts as they cover agronomy issues that matter most to you and your operation.

When Corn Becomes a Weed

Andrew Schmidt
Regional Agronomist
Volunteer corn plants are a nuisance for soybean growers because they grow quickly and are difficult to manage. Left uncontrolled, volunteer corn can lead to yield loss and can also serve as hosts for corn rootworm larvae. Timely herbicide applications are key to controlling volunteer corn in soybeans. In order to be effective, herbicides must penetrate corn’s waxy cuticle, which requires good spray coverage with the right products.
 
Here are a few tips to rid your soybean fields of volunteer corn plants that can rob yield.
 
  1. Reduce volunteer populations. Limit the number of dropped ears by protecting plants from insects and diseases that can promote weak roots and stalks. That may mean adding a fungicide or insecticide spray to your management program. Avoid ear and kernel loss at harvest by properly maintaining equipment and adjusting combines based on field conditions.
  1. Treat volunteers promptly. Corn can quickly outcompete soybeans if left untreated, leading to yield loss. A study by the University of Nebraska showed 5,000 volunteer corn plants per acre reduced soybean yield by approximately 20 percent.1   
  1. Use the right products. The waxy cuticle of corn plants can make them difficult to control if you don’t use the right products. Section® Three herbicide combined with StrikeLock® adjuvant from WinField United are an excellent option for controlling volunteer corn. Grassy weed herbicides including Section Three generally require the use of a high-surfactant oil concentrate for effective control. The addition of StrikeLock adjuvant helps the grass herbicide penetrate waxy corn cuticles for better coverage and control, while also providing industry-leading drift and deposition performance.
  1. Don’t skimp at application time. Depending on the size of the volunteers you’re trying to manage, you may need to increase herbicide and adjuvant rates to get effective control. Increasing the spray volume can help ensure you get adequate coverage of volunteer plants. Herbicide and adjuvant rates vary according to conditions, so consult with your local agronomist for specific treatment recommendations. 
Volunteer corn can be managed with timely action and the right products. Consult with your agronomist to learn about cost-effective ways to keep your soybean fields clean until harvest.
 
1. J. Alms, M. Moechnig, D. Deneke, D. Vos. “Volunteer corn effect on corn and soybean yield”. North Central Weed Science Society, 2008. Abstracts Volume 63

Answer Plot Program Insights Reveal Yield Opportunities

WinField United
Agronomy Team
The Answer Plot® program was created to give farmers greater confidence in their agronomic decisions. Since 1988, we have been transforming data from test sites across the country into expertise you can use on your farm. Here’s a look at five key insights from the program in 2017 that can help you move your operation forward this year and in the years to come.

1. Don’t leave 90 bushels on the table.
Spending smarter beats spending more. Response-to scores help you manage input decisions with a clear understanding of potential ROI. Through the Answer Plot program, we measure crop response to management strategies, including plant population, nitrogen application, continuous corn and fungicide application. The bottom line: Nearly 90 bushels could be at risk on any acre every year.
 
The data below shows the range of yield response to four key decisions that affect productivity and profitability. The better you can predict the results of your management decisions, the less risk you will carry and the more yield opportunity you will realize.

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2. Plant with confidence.
The best results come from matching every seed to the right management practices. To improve your odds of choosing the right seed for each acre, we collect data on how a vast range of products perform on fields just like yours. Using those results on 240 corn hybrids and 360 soybean varieties at nearly 200 Answer Plot locations, we populate the R7® Tool Top 10 feature, which finds the best 10 products for your fields and the conditions you face, including geography, soil type, maturity and irrigation.

3. Let the fungicide data do the talking.
Effectively managing mid-season input costs can make the difference between profit and loss. But when disease strikes, you have to protect yield. Response-to-fungicide (RTF) scores help you with seed selection and indicate where to scout for conditions that favor disease growth, so you can decide whether you can expect a return on a fungicide application and when to take action.
 
The Answer Plot program gauges RTF scores on 240 corn products every year. In 2017, based on data from 41 locations, average yield response after fungicide application was 11.2 bushels per acre. And the higher the RTF score, the higher the yield response.
 
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4. Keep nitrogen in its place.
Losing valuable nitrogen through air or soil is easy — and that’s not good for yield potential, the environment or your input budget. Nitrogen stabilizers slow the rate of nitrogen conversion so nutrients are ready and waiting for developing plants. The Answer Plot team is actively applying learnings from more than 400 independent research trials, which found treating fields with NutriSphere-N® Nitrogen Fertilizer Manager increased corn yield by an average of 10.0 bushels per acre compared to untreated plots.1,2

5. Seed treatment stops small pests from becoming big problems.
A well-chosen seed treatment can prevent damage from some of the biggest soybean yield threats, namely soybean cyst nematode (SCN) and sudden death syndrome (SDS). Based on testing at 25 Answer Plot locations with moderate to high SCN pressure, combining Warden® CX and ILeVO® seed treatments boosted soybean yield by 2.8 bushels per acre.
 
We hope you’ll join us in celebrating 20 years of insights — and bring your tough questions to an Answer Plot event this summer. See you at the plots!
 
Results may vary. Because of factors outside of Winfield Solutions’ control, such as weather, product application and any other factors, results to be obtained, including but not limited to yields, financial performance or profits, cannot be predicted or guaranteed by Winfield Solutions.
 
1. Koch Industries, 2018
2. Verdesian Life Sciences data on file

DRAs Really Do Matter

Dennis Christie
Agronomist
Once you’ve decided to plant dicamba-tolerant soybeans, be sure you’re ready to take the steps needed to ensure a solid return on your investment through more effective weed control. Using application techniques appropriate to new dicamba herbicide tank mixes will help protect yield potential while preserving the value of the technology for future seasons.
 
Follow the rules
Job one is to follow all label guidelines for tank-mixing herbicides before applying the mix to Roundup Ready 2 Xtend® soybeans or cotton with XtendFlex® technology. That means following directions for application timing and procedures, using approved nozzles and, in almost every case, adding a drift reduction agent (DRA) to the tank mix.
 
You’ll find lists of approved DRAs for each product on company websites. Specific requirements vary by state and can change over time, so double-check guidelines within a week of applying a low-volatility dicamba herbicide.
 
DRA 101
In general, DRAs help reduce off-target applications by making spray droplets larger. Larger droplets are better able to penetrate the canopy to reach surfaces of target weeds, which results in more effective control.
 
Larger droplets also means fewer droplets, so follow guidelines for spray volume to ensure good coverage. Most dicamba tank mixes should be applied at 15 gallons per acre, but be sure to check the label and consult your agronomist with any questions before making an application.
 
Aren’t all DRAs the same?
Even among approved DRAs, you will find performance differences. While all DRAs start out doing the job of increasing spray droplet size, some DRAs may not maintain that performance over time as they are subjected to recirculation within the spray tank.
 
Here’s why: Shear forces imposed on a spray solution moving through a spray system can cause DRAs to act differently. Some DRAs are more susceptible to shear forces, which reduces their ability to suppress fine droplets during application.
 
In testing multiple DRAs with new dicamba herbicide tank mixes using the WinField® United Spray Analysis System, we found some DRAs lost their ability to reduce the percent of driftable fines. However, OnTarget™ adjuvant continued to work after many revolutions through the spray pump.
 
We know OnTarget™ adjuvant will give you the best potential for return on your DRA investment based on comprehensive testing with the WinField® United Spray Analysis System, validated by in-field testing. The graph below shows reduced small particles in dicamba applications when OnTarget™ adjuvant was added to the tank mix.

 We have seen additional good results in field trials when OnTarget™ adjuvant and InterLock® adjuvant are used together in dicamba tank mixes. Adding InterLock® adjuvant at a rate of 1 to 2 ounces per acre will help improve consistency of spray droplet size for better coverage and performance.
 
Take time to plan your herbicide tank-mix strategy before application season heats up. Adding a DRA to a dicamba mix is the best way to get better return on your input investments and ensure good results from this needed weed-control technology for years to come.

XtendiMax® herbicide with VaporGrip® Technology is a restricted use pesticide. XtendiMax® herbicide with VaporGrip® Technology is not registered in all states and may be subject to use restrictions in some states. The distribution, sale, or use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. Check with your local Monsanto dealer or representative for the product registration status in your state.
 
ALWAYS READ AND FOLLOW DIRECTIONS FOR USE ON PESTICIDE LABELING. IT IS A VIOLATION OF FEDERAL AND STATE LAW to use any pesticide product other than in accordance with its labeling. NOT ALL formulations of dicamba or glyphosate are approved for in-crop use with Roundup Ready 2 Xtend® soybeans, Bollgard II® XtendFlex® or XtendFlex® cotton. ONLY USE FORMULATIONS THAT ARE SPECIFICALLY LABELED FOR SUCH USES AND APPROVED FOR SUCH USE IN THE STATE OF APPLICATION. XTENDIMAX® HERBICIDE WITH VAPORGRIP® TECHNOLOGY AND IN CROP USES MAY NOT BE APPROVED IN ALL STATES. Contact the U.S. EPA and your state pesticide regulatory agency with any questions about the approval status of dicamba herbicide products for in-crop use with Roundup Ready 2 Xtend® soybeans, Bollgard II® XtendFlex® or XtendFlex® cotton.
 
Roundup Ready 2 Xtend® soybeans contains genes that confer tolerance to glyphosate and dicamba. Bollgard II® XtendFlex® cotton contains genes that confer tolerance to glyphosate, dicamba and glufosinate. Glyphosate will kill crops that are not tolerant to glyphosate. Dicamba will kill crops that are not tolerant to dicamba.
 
Glufosinate will kill crops that are not tolerant to glufosinate. Contact your Monsanto dealer or refer to Monsanto’s Technology Use Guide for recommended weed control programs.
 
Individual results may vary, and performance may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible.
 
ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Bollgard II®, Genuity®, Monsanto and Vine Design®, Roundup Ready 2 Yield®, Roundup Ready 2 Xtend®, XtendFlex®, XtendiMax® and Vaporgrip® are trademarks of Monsanto Technology, LLC

Spoon-Feed Crops for a Yield Advantage

George Watters
Agronomy Manager
Historically, many farmers have applied all their fertilizer in late fall or early spring. Although this practice can provide a sound foundation for crop growth, nitrogen and other key nutrients can be left vulnerable to environmental loss when applied all at once.   
 
Lost fertilizer results in wasted input and potential harm to the environment. Answer Plot® research suggests that spoon-feeding fertilizer throughout the growing season may result in a yield boost, because applying smaller amounts of nutrients when plants need them is more efficient from a plant uptake and use perspective.
 
Research backs the benefits
Data from 2016 Answer Plot® trials showed a 7.4 bushel per acre yield advantage in corn when a portion of the total nitrogen application was delayed until the V10 growth stage.1 The crop’s need for nitrogen increases rapidly toward the time of tasseling, so it makes sense that a later application would result in a yield bump as the plant begins shifting resources to fill out its ear.
 
A recent study by Purdue University found that modern corn hybrids have a higher demand for nitrogen later in the season, and thus may more likely benefit from a split application.2 Response-to-nitrogen scores from Answer Plot® trials can help identify corn hybrids that may benefit from spoon-feeding later in the season.
 
Start with sampling
Any sound fertilizer plan should be based on soil analysis from a quality laboratory. Soil testing guides application of crop nutrients and provides insight into the nutrient status of a field. Once you know what nutrient levels are in your soil, you can start optimizing your fertilization program.
 
Starter fertilizers like OptiStart® help provide a solid foundation for early plant growth by placing nutrients close to young roots for improved uptake. This promotes more vigorous early-season growth so plants are more tolerant to stress. Answer Plot® research has shown up to a 7 bushel per acre advantage in corn when starter fertilizers are used, especially in colder soils.3
 
An in-season tissue test will indicate real-time nutrient levels in the plant, which can guide additional fertilizer needs as the season progresses to help protect yield potential. Contact your local WinField United retailer to help develop a season-long fertilization program.  
 
With the growing season on the horizon, we’re here to help you with your holistic plant nutrition plan. Next, we’ll explore how modeling programs can help manage nutrients and the importance of micronutrients in your fertilization program. We’ll continue to dig into all aspects of plant nutrition throughout the year right here on the Growing Knowledge blog, so be sure to check back for more plant health tips.
 
1. Based on an average of 15 Answer Plot® locations.

2. Late Season Nitrogen Fertilizer Placement, Timing and Rate Responses in Modern Corn Hybrids; T. Vyn, et.al.; Purdue University; 2016 Indiana CCA Conference.

3. Based on an average from 37 Answer Plot® locations.

Consider Rotation for Cleaner Corn Fields

Jim Eggerichs
Technical Seed Manager
Last year, nearly 91 million acres of corn were planted across the country. That’s a lot of land to keep weed-free. But including crop rotation as part of your comprehensive weed management strategy can help ease the pressure of controlling troublesome weeds.
 
Changing the weed spectrum
When crops are rotated, management practices change to accommodate a specific crop. This is an important factor in weed control because weeds are less likely to become adapted to an environment that continuously changes.
 
Consider a corn-on-corn field. Each year it is planted and harvested around the same time. Similar fertilization and herbicide programs are used year after year. And it’s very likely that the same tillage practices are used on this field over consecutive years. The problem with this crop production plan is that it allows weeds to become better adapted to their environment, making them more difficult to control with the same management practices.
 
On the other hand, consider a field where alfalfa is added into a rotation with corn. The management of the added alfalfa crop can have a big impact on the weed spectrum in the field. Herbicides used to manage weeds in alfalfa are different than in corn, so weeds are exposed to different sites of action for control. In addition, alfalfa is harvested several times during the year, exposing weeds to mechanical damage prior to seed reproduction. The extra cuttings could significantly cut down on the number of weed seeds that end up in soil. This is just one example of how crop rotation can work to change the weed spectrum in a field.
 
Outsmart weeds
As you finalize crop plans think about how your production practices may be contributing to weed populations. If your fields are not in rotation, consider adding one to disrupt weed life cycles. If you plant the same crop year-after-year choose seed products with excellent emergence and early vigor characteristics that better compete with weeds early in the season before crop canopies are established.
 
Work with your trusted advisor to help develop a crop plan that can ease the stress of managing troublesome weeds.

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