Crops

With weed control, do the right thing

Written by Dr. Jason Weirich on .

With all the talk about weed control and the issues surrounding it, I find it fitting to discuss that topic this month. Even with the drop in commodity prices, weeds are still going to emerge and compete with your crop. When it comes to weed control, we can’t afford to give up on doing the right thing.

Herbicide resistance has driven the adoption of residual herbicides in corn and soybeans. Overlapping residual herbicides are still the best weed control practices you can implement on your farm. It might be the only way we can preserve multiple herbicide trait packages.

Let me explain. The overuse of Liberty as a source of weed control makes me believe it’s only a matter of time before we lose the effectiveness of that technology. I know many growers are using overlapping residuals with the Liberty Link system, but we also have growers who are not. This single mode of action on off-label weeds leads us down a road that doesn’t end well for the technology.

When we look at the Roundup Ready system, overlapping residuals are controlling our driver weeds such as waterhemp, Palmer pigweed, marestail, giant ragweed, etc. Yes, we do have issues at times with failure to get that timely rain to activate the residuals, but it is the best option we have.

In the Roundup Ready system, we have seen increased over-the-top applications of the class of herbicides known as PPO (protoporphyrinogen oxidase). With timely applications, we can usually do a good job of cleaning up some of the escaped weeds. But every year, we all can pinpoint that one field that gets hit with everything but the kitchen sink. We have seen a rise in performance issues with these type of products (Cobra, Blazer, Flexstar, etc.) even on labeled weeds. Over-the-top usage of PPO has provided much relief from some of the herbicide resistance issues we have seen, but it appears that is coming to an end, at least for the time being.

Now let’s talk about the Xtend cropping system. By now you are aware of the protocols that MFA has put in place to help steward this program past the 2018 season. I feel that this is the best way to keep this technology for the future. You may ask, “Why past 2018?” When these products received the label for the 2017-18 season, it was good for two years. This season will be pivotal for the future of this technology. I believe that this system can be stewarded, but we must utilize overlapping residual herbicides to make it so. We simply must follow the label and all the guidelines to help protect this technology.

What does that mean? Well, we know that the label restrictions will limit the days in which applications of these products can be made during the season. If the spraying conditions aren’t right, we must stop application or change our weed-control tactics. We have to follow the label, or we could lose the use of this herbicide. This chemistry isn’t a silver bullet, and it shouldn’t be treated like one.

Does your integrated weed management plan consider the use or non-use of dicamba? Does your plan utilize overlapping residuals in all cropping systems? Does your plan have the proper adjuvants and/or drift reduction agents listed? I hope that by the time this reaches your mailbox, you already have that plan in place. If not, please reach out to one of our MFA or affiliated locations to develop yours today.

Lose the loss with nitrogen stabilizers

Written by Dr. Jason Weirich on .

Does this product work? That’s the question I often get about nitrogen stabilizers. There are plenty out there in the marketplace these days. Pick up any farm magazine (including this one), and you’ll see some type of advertisement or article about nitrogen stabilizer. I know this causes a lot of confusion, so allow me to explain more about their purpose and performance.

Nitrogen stewardship is one of the most important things we can do to protect our yield and environment. Nitrogen stabilizers are commonly used to protect against nitrogen losses through volatilization, denitrification and leaching.

It’s important to understand these processes, so I’m going to get technical. Nitrification occurs when ammonium is converted to nitrite in the soil by nitrosomonas bacteria, and then further oxidized to nitrate by nitrobacter bacteria. A majority of the nitrogen taken up by the plant is in the nitrate form, but most plants can also take up ammonium.

Once in the nitrate form, the nitrogen is subject to loss. Nitrate moves freely throughout the soil profile with moisture. In coarse-textured, well-drained soils, nitrate can leach below the root zone and become unavailable to the crop. Nitrate is also subject to denitrification, a biological process that converts nitrate to a gas that is lost to the atmosphere. This occurs in waterlogged soils.

Currently there are two proven nitrification inhibitors on the market: nitrapyrin and dicyandiamide (DCD). Nitrapyrin has been used since the 1960s. It has long been marketed as N-Serve and most recently as Instinct, an encapsulated product for dry and liquid fertilizers. Instinct can also be used in liquid manure. DCD is the nitrification inhibitor in Agrotain Plus and Super U.

Growers often ask me just how long N-Serve protects nitrogen in the soil. A general rule of thumb is 90 days for fall-applied nitrogen. Keep track of those days by counting the date of application until soil temperatures drop below 40 degrees. Resume counting in spring when soil temperatures warm above 40 degrees. In the spring, expect eight weeks of activity from an April 15 nitrogen application, seven weeks from a May 1 application and six weeks from a May 15 application. Research indicates about a 7-percent yield advantage from fall-applied nitrogen and a 5-percent advantage from spring applications.

Another nitrogen loss avenue is volatilization—the loss of free ammonia to the atmosphere. This process has several steps. First, an enzyme (urease) in the soil and organic residue act on urea and convert it to an unstable form, which can quickly change to ammonia and carbon dioxide. With ideal conditions, this unstable form is converted to ammonium and is available for plant take-up.

However, when conditions are less than ideal, the ammonia can be lost into the atmosphere. Factors that influence this process are urease activity, temperature, soil moisture, application method, soil pH and cation exchange capacity, a measure of the soil’s ability to hold positively charged ions.

The greatest potential for loss occurs when there are high amounts of residue on the soil surface and the nitrogen source is applied on top of the field. In MFA’s trade territory, the most common concern I hear from growers is about how much nitrogen they have lost when an application is followed by a week of hot, windy and dry days.

Research shows that the potential for nitrogen losses through ammonia volatilization can be reduced when using a urease inhibitor to slow or delay hydrolysis. Slowing this process gives Mother Nature a chance to provide precipitation that moves urea into the soil. The most effective inhibitor currently available is Agrotain (nBTPT).  

Then the question becomes, “How much nBTPT is getting put on my urea?” A few of the products on the market today state they have nBTPT in the jug.  While that may be true, be sure you find out how many parts per million the product provides on a ton of urea.

Nitrogen loss can be one of the most yield-limiting factors in the field. Keeping nitrogen in the root zone and available for the crop not only provides a return on the investment for the grower but also has a beneficial environmental impact by reducing losses into the water and air. Check with your MFA or AGChoice location for more information on using nitrogen stabilizers this spring.

Manage fields to influence infiltration

Written by Matt Hill on .

Water infiltration, the process by which water on the ground surface enters the soil, is a critical component of the water cycle. The goal is to keep infiltration rates as high as possible. Reduced infiltration has negative effects, some catastrophic.

Many factors influence infiltration, and it is important to remember that a “good” or “bad” measurement of any factor independent from the others does not indicate what the infiltration rate will be. They all work together to form a composite measurement that determines how well water is able to enter the soil profile at any given location. We can’t control some of the factors, but it’s good to know how they influence infiltration rates so we can consider them when choosing management strategies.

We know that infiltration is reduced in cities with every new building, each square foot of parking lot and every concrete drainage ditch. The drastic decrease of infiltration in urban areas leads to local drought, severe flash flooding and nearby streams full of whatever pollutant washed off the streets.

Inadequate water infiltration isn’t limited to the concrete jungles. Many crop fields and pastures have reduced infiltration, too. While the evidence isn’t as dramatic as cars floating down a street, it’s important to understand that reduced infiltration can result in increased erosion, ponding and drowned-out spots, decreased water quality in streams and ponds and, most importantly, inadequate soil moisture for optimum crop growth.

Water relies on voids in the soil to enter and move through the profile. The size and amount of voids are affected by factors such as soil particle size, amount of aggregation, earthworm tunnels and root channels. Frequent tillage is the most common reason infiltration is decreased. Every time the soil is tilled, the pore spaces are broken down and filled in, creating less space for water to enter.

We also need to be able to slow water down enough for it to infiltrate. If water is rushing across the slope in a field or pasture, most of it is not going to get into the soil, no matter how good the soil structure. Places with varied topography or little residue are at risk for poor infiltration just as they are for erosion.

Keeping tillage to a minimum is the primary management strategy to increase infiltration. That will allow for better soil aggregation, less potential for compaction and more abundant soil biology. Keeping crop residue on the surface and using cover crops will impede water flow and give it more time to infiltrate.

MFA Crop-Trak consultants will work with you to identify the best management strategies for your operation, including how to maximize infiltration and crop yields. Your local NRCS office is also a great place to get more information about the importance of infiltration and cost-share programs that are available to help pay for practices to address infiltration concerns on your farm.  

This complex topic is difficult to describe without illustration. The University of Missouri has conducted research about water infiltration and drought mitigation. A video discussing the results of that study is available on YouTube at https://youtu.be/o_d18qX7VFk. NRCS staff have rainfall simulators that are another great demonstration of how different management strategies affect infiltration. If you haven’t seen one, search for “rainfall simulators” online to find several videos showing those demonstrations.

Keeping it under wraps

Written by Marc Epp on .

Forages are at their best when first cut, but quality begins to deteriorate quickly between harvest and storage. An alternative to putting up dry hay is baleage, also called haylage or round baled silage. With baleage, forage is baled and wrapped in plastic at high moisture, up to 65 percent. Inside the plastic, the forage is ensiled and quality is preserved. This storage method minimizes weather risks that can affect hay quality while drying in the field. For regions that receive frequent spring rain and/or high humidity, the method offers producers flexibility in the field and allows less time between cutting and storage.

When it comes to harvesting and handling, putting up high-quality baleage is the same as conventional dry hay. Its quality is a function of forage maturity when cut and how it’s subsequently handled during baling and storage. If the bales are too wet or dry and spoilage occurs, there can be significant losses in value. As long as baleage is done correctly, however, there are decreased harvest losses and increased quality compared to the same-quality dry hay.

Here are some tips for harvesting, wrapping and feeding the highest-quality baleage:

Cutting and prepping:

  • Cut forage in late-boot to early-head stage to maximize sugars and the fermentation process.
  • Cut after the dew has dried from the standing forage. Using the moisture in the plant—not on the outside—is crucial.  
  • Set the mower to lay the forage as wide as possible to enhance even drying. Forage containing less than 40-percent moisture or much above 65 percent should not be baled for silage to avoid excessive molding or spoilage.
  • Rows should not be tedded. This will alter the straight orientation of the stems, which will reduce the efficiency of a tight bale.

Baling:

  • The key is to eliminate as much oxygen as possible. Making a tight bale will help do this.
  • Research has shown that exceptional baleage can be made without the use of additives. This is true even when ensiling legume crops that have more difficulty reaching the pH range of stabilized fermentation. However, inoculating with Lactobacillus buchneri strains can accelerate the rate of fermentation and improve stability of the silage during feeding. This is particularly important if the baleage is to be fed during the summer or in warm climates.
  • Pre-cutters in the baler will increase bale density and improve fermentation.
  • When using in-line tube wrappers, create uniform bale sizes as much as possible to eliminate unevenness when stacked against each other. Irregularity of the tubes may expose more oxygen to the bale.
  • Wrapping bales at the proper moisture content (45-60 percent) will help minimize the risk of botulinum toxicosis, caused by a potent bacterium in the environment. The spores remain dormant until exposed to anaerobic conditions and the right nutrients, which can cause them to germinate, grow and release toxins.

Storing:

  • Ideally, bales should be wrapped immediately after baling, but research has shown waiting up to 12 hours has minimal effect on forage quality. Wrap that is typically 1 mil thick, when overlapped, should give coverage thickness of 4-6 mil of plastic and 50- to 55-percent stretch. Wrap in dry weather for plastic to stick.
  • Store bales on level ground free of rocks or other sharp objects that may puncture the plastic. Orient the bales to minimize constant direct sunlight in a single area, such as in a north/south line. This will reduce sweating and deterioration of the plastic. Periodically check the bales for tears or holes and fix right away. Use tape made for the plastic, not duct tape.

Feeding:

  • Some mold will form around the edges. This is usually just at the surface, and animals will eat around it. It will not significantly harm the animal if some is eaten.
  • For bales to appropriately ferment, it is best to wait six to eight weeks before beginning to feed them.
  • If forages are baled at more than 60-percent moisture, feed these first as the shelf life is only about three months. At 30- to 40-percent moisture levels, feed value declines after six months. In general, forages baled at 40- to 60-percent moisture will maintain feed value for about 12 months as long as the plastic is intact. However, even when baled at the appropriate moisture level and the plastic has a minimal amount of holes, it is best to feed baleage within nine months.

Manage diseases with multi-faceted approach

Written by Jason Worthington on .

When considering seed treatments, we usually think first about their necessity and then what products will work for a particular field. We don’t often think about stewardship of these products. I am guilty of it as well. When discussing seed treatments, I usually talk about their benefits and product selection with a mind toward disease control. Stewardship is a second thought.  

However, when we look at available seed treatment products compared to the spectrum of seedling diseases, we quickly realize the importance of stewardship. There are few effective modes of actions available. To conserve seed treatments as a crop protection tool, they must be used in conjunction with sound cultural practices.

In this part of the world, when we think about resistance, herbicides are our first concern. But resistance management should be considered when dealing with any pest, including seedling diseases. When you break down our driver diseases and effective sites of action, the need for resistance management becomes much more apparent. There are essentially six different sites of action, or classes of fungicides, used in seed treatments today, compared to 19 classes of herbicides.

But, just as not all herbicides are effective on all weeds, not all seed treatment fungicides are effective on all seed-borne or seedling pathogens. When we look at our driver diseases used to make seed treatment decisions, they fall into two classes: water molds (phytopthora and pythium) and true fungi (rhizoctonia and fusarium). When we look at these groups separately, there are only three modes of action and four sites of action to control true fungi and a mere two sites of action effective against water molds. With so few choices coupled with logistical difficulties of handling multiple seed treatments, rotation of fungicides becomes complicated to implement as a resistance management strategy.

So what are our options? First, seed treatments cannot be our only defense against disease. Just because a fungicide is applied to the seed does not mean we can ignore other factors that favor disease development. Remember the components of the disease triangle from biology class. To have a disease, we need three things: a host, a pathogen and a favorable environment. Seed treatments attempt to address one piece—the pathogen—but additional management can take care of both the environment and the host.

We can manage the environment by waiting for soil conditions to be correct. While not always possible, this is the best line of defense against most soybean seedling diseases. The diseases of concern all have a preferred temperature range. Avoiding temperatures in the ranges outlined in the accompanying table can decrease the likelihood of infection.

Perhaps more important than disease is proper soil moisture. Planting into fields with adequate—but not excessive—moisture is ideal for numerous reasons. Not only do many fungal diseases thrive in saturated conditions, but you also want to avoid compaction, which compound saturated conditions, hamper seedling growth and contribute to disease.

We can also manage the susceptible host component of the disease triangle. Selecting varieties with resistance to soil-borne diseases such as phytopthora or sudden death syndrome is the obvious place to start, but soil conditions can also have a huge impact on the amount of time a seedling remains vulnerable to infection. Anything that limits the amount of time a seed spends underground and promotes rapid growth of a young plant lessens the time a plant remains vulnerable to infection. We see this time and again in years where SDS is common. The fields affected most severely often have seedlings that endured stressed or prolonged emergence periods. Think about how much more vulnerable an infant is to the flu than a healthy adult. Proper temperature, moisture, depth and seed placement all impact the growth and development of the soybean plant just as much as the disease.

Managing diseases takes a multi-faceted approach. Over-reliance on any one method of control—cultural or chemical—can lead to disappointing short-term results. In the long term, that reliance can lead to the development of resistant pathogens. It is important keep integrated pest management strategies at the front of our decision-making process for immediate success and continuing efficacy of our control options.

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