Give your weed control investment a better chance

Written by MFA STAFF on .

Proper choice and use of adjuvants helps crop protectants do their job

With weed challenges from the previous growing season and new herbicide technology on the market, paying attention to adjuvants takes on new importance in 2016.

The increase in the seed bank from an odd growing season and the proliferation of herbicide-resistant weeds means that weed management for the next growing season will be crucial. If there were major weed escapes, it may take years to return the seed bank to a previously lower level. In the upcoming growing season, getting adjuvants right can give your weed control program a beneficial edge.

Adjuvants improve weed control in various ways. As new herbicide technology comes to the field, one important way adjuvants contribute to weed control success is keeping spray on target. Drift control will be a priority as dicamba and 2,4-D herbicide platforms reach fields.

Adjuvants also play an important role in the efficacy of herbicides once they hit target plants. All leaves have a waxy covering (cuticle) surrounding the outside of the leaf. It’s a biological defense mechanism for the plant. The covering reduces fungal problems by allowing water to run off the leaf and helps protect the leaf under harsh environmental conditions. A herbicides has to pass through this waxy barrier to its job. Adjuvants play a role in aiding herbicide movement into the plant. There are three types of adjuvants that work directly with herbicide chemistry: surfactants, concentrated crop oils, and fertilizer salts. The herbicide a grower uses will determine which adjuvant is recommended.

Surfactants have many different roles depending on the chemistry used. Cationic and anionic (positive and negatively charged) surfactants are great wetting agents and some cationic surfactants are pre-formulated with herbicides.

Nonionic surfactants like Astute Extra, Astute and Astutue Lite do not have a charge and can be used with a wide variety of herbicides. These are not affected by ions in hard water. Nonionic surfactants are good dispersing agents. They are soluble and stable in cold water and have low toxicity to plants and animals.

Silicone-based surfactants work even better than nonionic surfactants. They are efficient at dispersing water droplets and are humectants (humidity creating). Combining these qualities increases the amount of herbicide entering the plant in addition to reducing the time for herbicides to become rainfast. However, silicon surfactants are not compatible with herbicides that need small concentrated deposits, such as glyphosate.

Regardless of surfactant, they all share a goal—to disperse water droplets. Surfactants aid in droplet creation by breaking the surface tension of water, which allows droplets to spread out rather than bead up. This is especially important when using contact herbicides such as Cobra. Contact herbicides do not move through the plant, so coverage area is extremely important.

Concentrated crop oils and methylated seed oils like Relay, Xpond and Soy Plus enhance uptake of herbicides by penetrating the cuticle. The waxy cuticle is made up of fatty organic compounds. Because oil-based adjuvants have similar chemical properties, the oils and cuticle are chemically attracted to one another. That provides better penetration of the herbicide through the cuticle. Oils also keep herbicides in a liquid state longer, further aiding herbicide uptake.

Methylated seed oils are smaller less complicated molecules, which makes them lighter and more effective at penetrating the cuticle. Crop oils and methylated seed oils must also contain an emulsifier and require agitation to keep the oil suspended in water, preventing buildup on the water surface.

AMS “conditions” hard water (AMS Advantage and Waypoint) high in magnesium and calcium ions for herbicides, especially glyphosate, which binds to these ions reducing its effect. Adding AMS before adding glyphosate to the mix can protect the herbicides active ingredient against binding.

MFA’s line of water conditioners, including AMS Advantage, Waypoint, Overide and Impetro are good options if hardwater is a obstacle.

Of course, the pesticide label is the primary source to consider when choosing an adjuvant. Here are some things to consider when the label provides you a choice.

• If both oil concentrate (crop or vegetable oil) and non-ionic surfactant are options, consider nonionic surfactant under normal weather conditions if weeds are small clearly within label guidelines. If weeds are stressed from dry weather or more mature, their cuticle material will likely be thicker. Use oil concentrate in these conditions.
• If labeled, try to include oil concentrate to control grass weeds.
• Use nitrogen fertilizer only if it is recommended on the herbicide label.
• If your herbicide has high potential for crop injury, consider nonionic surfactant instead of oil concentrate.
• To improve crop safety, do not include oil concentrates with plant growth regulator-type herbicides (i.e., dicamba, 2,4-D, etc.)
Herbicide manufacturers research the best surfactants to use with their products. Newer herbicides tend to have labels with very specific directions for amount and type of surfactant. However, some herbicides have more general recommendations in the label.
A word of caution: adjuvants are not regulated by the EPA and therefore you may hear exagerated claims about what the products can do. Make sure you buy adjuvants from a reputable source. Here are some red flags for products that might sound too good to be true:
• It is only available on the internet.
• Any claim that includes “resistant weeds” in its purpose
• An unknown company that is located outside MFA’s market area.

If you have questions about the best adjuvant for your weed control program, contact a local MFA agronomist HERE or contact This email address is being protected from spambots. You need JavaScript enabled to view it..

Make a plan for manure

Written by Cameron Horine on .

Livestock operations can benefit from foresight in nutrient management plans

Do you own a dairy farm or have a swine operation? Or maybe you have poultry barns. If you have any of these you understand the large quantities of manure that can be collected. What do you do with all of the manure and/or bedding that is accumulated every day? Do you export it to another producer or do you apply it as fertilizer on your farm?

However you handle the manure is up to you, but to do it properly and safely you may need to have a comprehensive nutrient management plan (CNMP) in place. A CNMP is an organized five-year plan specific to your operation. It allocates the manure produced on your operation and provides a plan to properly use the nutrients on your farm based on criteria including topography, crops, soil tests, etc.

Every operation is different, and every CNMP will be different. There are many factors that affect a CNMP. Two of the main factors is having proper soil test results and manure analysis. The manure analysis will be dependent on animal type, animal growth stage, diet and storage. Knowing the analysis of the soil and manure allows for proper allocation of manure to each field based on the crops’ needs for the year.

If handled correctly, manure can be a beneficial resource. Some of the benefits include improving your soil tilth and structure, increasing water holding capacity of soil, and increasing growth of beneficial soil microbes and organisms. On the other hand, if handled incorrectly, it can be a waste and an environmental hazard. This is why a CNMP that has been properly put in place for your operation is essential and can save you from negative implications with the government and your neighbors.

In many cases, manure alone will not satisfy the crop’s nutrient needs and supplemental fertilizer will be necessary to achieve your yield goals. The CNMP provides you with a detailed report of planned manure applications and supplemental fertilizer for each field. These detailed reports help you to make management decisions on your farm. With a CNMP you will protect the environment, get the best use from your nutrient assets and maximize your crop or forage yields.

The cost of the CNMP varies based on the type of operation and the size. However, the cost is refunded by the USDA/NRCS.
If you need a CNMP or you currently have one that needs to be renewed, contact your local MFA or affiliate.

Cameron Horine is a staff agronomist for MFA INCORPORATED. Contact This email address is being protected from spambots. You need JavaScript enabled to view it..




Make room for monarchs

Written by Dr. Jason Weirich on .

It might surprise you to find me writing about monarch butterflies in this space. But I am. There has been a significant decline in the monarch population over the past few years. It is easy to point fingers to others, but it is time to admit that a shrinking habitat is likely the cause of monarch decline.

Monarch butterflies overwinter in central Mexico during the area’s dry season, which is right about now. Increased illegal logging in central Mexico has reduced the monarch’s overwintering habitat, but that is not the sole cause for its decline. The rapid adoption of non-selective weed control programs has reduced the amount of habitat in the butterfly’s summer breeding grounds. This is a factor in which our trade territory plays a vital part.

As a weed scientist, talking about planting milkweed goes against what I have done in the past. Milkweed has been considered a pest to most of agriculture, and we have sought to control or eradicate milkweed from our farms. Of course, I am not saying we need to totally upend weed management. However, there are some things that you and I can do to help make sure the monarch butterfly doesn’t get listed as an endangered species, or worse, go extinct.

Yes, it will involve planting milkweed. This isn’t the only thing the monarch needs in order to rebound, but it will play a key role.

As I look at the Midwest and see acres of CRP, community gardens, state and federal parks and our spacious backyards, I see places that make ideal candidates for monarch habitat and foraging.

Timely mowing and herbicide applications can also help protect the monarch population. Try to avoid mowing this kind of habitat when the monarchs are using it. This will allow them to continue the life cycle and make the trek north or south.

Common milkweed, swamp milkweed, butterfly weed, and whorled milkweed would be the species of choice in our trade territory. There are numerous facts available on the following links that can help you establish habitat for monarchs and pollinators.

While we might not see eye-to-eye on every topic, we do have a common goal: to sustain monarch and pollinator populations while using sound science for the foundation of our decisions. Look for more information in the coming months about monarch and pollinator issues.

Watch for seedling soy disease this year

Written by Steve Fairchild on .

If you see something, say something. That’s the mantra for national security, but it can help in your soybean field, too. The early season disease damage you see in the field this year will have an effect on yield at the end of the season. And the fungus will likely be waiting for the next soybean crop, too.

Soybean seedling disease pressure is most common in cold, wet conditions, which are stressful on plants and give diseases a foothold. Compacted soils and heavy clay also tend to increase chances of fungal disease.

The canary-in-the-coal-mine to watch in spring are low-lying areas and wet spots where seedlings often are first to exhibit disease.

What to watch for:

Pythium seed decay and damping-off. Pythium is the most common fungus causing damping-off in soybean. It is more likely to occur on soybeans that are planted early in the season in colder soils. Infected plants have a rotted appearance and can easily be pulled from the soil.

Phytophthora seedling blight. Phytophthora is a soil-borne fungus that causes seed decay, pre- or post-emergence damping-off and seedling blight of soybeans. It is most common in soybeans planted in warm (greater than 65 degrees) and wet soils. The seedling blight phase may cause yellowing, wilting and death of the plant. It is more likely to occur in low-lying or poorly drained areas.

Rhizoctonia seedling blight. Rhizoctonia is another common soil-inhabiting fungus that can cause seed decay and pre-emergence damping-off of soybean seedlings. Symptoms of rhizoctonia are found on seedlings, young plants and even older plants and consist of localized red to reddish-brown lesions near the soil surface. Infected plants may be stunted or less vigorous than healthy plants, causing uneven stands. Severe infestations and dry weather may cause death of the plant. Like phytophthora, rhizoctonia prefers warmer soils.

Fusarium seedling blight. Fusarium seedling blight is caused by a soil-inhabiting fungus and causes weak or stunted plants and uneven stands. The disease causes a rot of the root system while the aboveground portion of the plants may start to turn yellow. Plants may eventually wilt and die during periods of warm to hot weather. The disease is most severe when the soil is saturated and soil temperature is around 57 degrees at planting, conditions that are not as common this year.

Charcoal rot. Charcoal rot is one of the most common diseases found in soybeans. It typically shows up as a mid- to late-season disease on mature soybeans, but can also occur early in the season on seedlings. Symptoms include reddish-brown discoloration from the soil up the stem that may become dark brown to black as the disease progresses. Plants may die if conditions become hot and dry.

There are several approaches to manage seedling disease. The notes you take this year will help you decide which management techniques will best suit the field the next time it is in soybeans.

Seed selection and seed treatments are the key tools. Obviously, you should select resistant or tolerant seed cultivars. Soybean seed lines have disease ratings for Phytophthora root rot (look for the PRR). Keep records of cultivars grown in order to track PRR races that may be present in the field.

Fungicide seed treatments have become more popular as seed costs increase and crop protection companies fine-tuned the offerings. They consistently provide enough yield benefit to pay for the practice. A Kansas State study showed an average yield increase of 2.5 bushels per acre over an eight year period.

But chemistry is only so powerful. Your crop scouting is important for future success. Seed treatment active ingredients should provide control of the pathogens you’ve noted in the field. And it is worth noting: active ingredients that control Pythium and Phytophthora diseases do not affect Rhizoctonia and Fusarium species. Similarly, fungicides that are active against Rhizoctonia and Fusarium have little effect on oomycetes. The University of Missouri has a useful guide on soybeans that includes photos to help identify diseases. Download it at:

If you have questions about diagnosing or treating soybean seedling disease in your fields or about replant decisions, contact your local MFA agronomist.

Fine-tune in-season nitrogen

Written by Jason Worthington on .

In-season nitrogen applications on corn and wheat have long been a part of Midwestern fertility programs. It is rare that wheat fields don’t receive a topdress application of nitrogen—if not two spring applications.

In-season topdressed nitrogen in corn is increasingly common whether it comes as a planned application or as a rescue application.

The perennial question that growers and applicators ask prior to the in-season topdress is how much nitrogen should be applied. That, of course, is the million-dollar question. If you answer it right, you get maximum yield for the input cost. If you answer it wrong, you either leave yield on the table or waste inputs.

Applying the right amount of in-season nitrogen is going to depend on a multitude of factors including soil organic matter; amount of nitrogen applied pre-plant; amount of nitrogen mineralization in the given year; yield potential of the crop; amount of nitrogen leached; amount of nitrogen denitrified; the previous crop, nitrogen stabilizers used, and more. You can see from that list of variables that the right topdress rate of nitrogen won’t be the same every year. Beyond season-to-season variability, changes in topography and soil type within the same field means the appropriate rate will not necessarily be the same from one end of the field to other.

We now have decades of experience in variable-rate fertilizer application. Through this experience and fine-tuning our abilities to collect yield data and soil test information, we have created very accurate recommendations for nutrients like phosphorus and potassium. Building an accurate variable-rate nitrogen recommendation has been more elusive. Improvements on variable-rate nitrogen are hitting the marketplace, however. Choices growers have right now basically come from one of three categories: machine-mounted crop sensors, aerial imagery or nitrogen models.

Crop sensors

Of variable-rate topdress options available, first to the market were crop sensors mounted to nitrogen application equipment. These on-the-go systems, such as AgLeader’s OptRx, work by reading near-infrared light reflected off of target plants. Dark green plants with sufficient nitrogen absorb more and reflect less light than lighter green plants that need more nitrogen.

For variable-rate topdressing with these systems, the first step is to measure areas of sufficient nitrogen and deficient nitrogen in the field with the sensors by driving over the field.

Once initial measurements are taken and application begins, the sensors continuously read the amount of light reflected. Application rates are calculated and adjusted on the fly by the computer and variable-rate controller on the machine. This process is very convenient due to the fact the applicator doesn’t need a recommendation built beforehand. The recommendation is built on the spot by the need of the plants. On the other hand, that means you won’t know how much nitrogen product is required until after application is completed, which can lead to challenges with product delivery.

Aerial imagery

Using aerial images to determine a variable-rate nitrogen recommendation on a field is similar to the principle behind on-the-go sensors. In this approach, the reflectivity of target plants is acquired by an aerial image to determine the topdress nitrogen rates throughout the field. The information can be measured in several different spectrums, but the theory is the same—crops with adequate nitrogen will be greener than those with inadequate nitrogen. The major difference between aerial and on-the-go measurements is that the aerial images can be turned into nitrogen recommendations before the applicator heads to the field, so the total amount of nitrogen is already known.

MFA is evaluating software that processes high-quality images captured from satellites, airplanes or even a grower’s drone to create in-season nitrogen recommendations. The processing time involved in building the recommendation is the challenge. Timing becomes an issue as well. Aerial images and crop sensors work best when the crop canopy is closed, which ensures reflected light is coming from leaves, not bare soil.

Nitrogen models

Nitrogen models work much differently than sensing technologies. Instead of taking a light reading to determine the nitrogen sufficiency of the crop at a specific point in time, nitrogen models attempt to measure the factors that affect nitrogen availability, loss, and a crop’s yield potential to create a nitrogen recommendation. The variables listed above are entered into the model or measured throughout the season to figure nitrogen loss and mineralization. The model’s goal is to predict nitrogen needs for the remainder of the season. This is advantageous from the standpoint that recommendations can be made with some added accuracy over typical flat-rate recommendations. However, if any information is left out or unaccounted for the accuracy of the nitrogen model will decrease. Where sensing or imaging technologies measure current conditions, models are working off of a lot of calculations and assumptions.

Regardless of the method used to develop more accurate in-season nitrogen recommendations, these new options should excite growers. The goal of variable-rate technology with nitrogen and other nutrients is to make sure the right rate is applied in the right place. This is good stewardship for the environment and leads to increases in agronomic productivity and cost efficiency of your inputs.


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