About Your Fields March 5, 2018
About Your Fields
In this issue:
1. Adjuvants, More Than Just Soap and Oil
2. News That Caught Our Eye
Adjuvants, More Than Just Soap and Oil
In today's market place adjuvants play a larger role than they did previously. Gone are the days when you bought an adjuvant that may have been nothing more than a form of soap that would help spread a chemical or an oil that would help the chemical penetrate the leaf's cuticle. Adjuvants today help with absorption without the leaf burn that we saw previously. Some adjuvants may have multiple properties that previously you had to mix in multiple adjuvants to achieve the same effect. Also with the advent of the Dicamba age you have to pay attention to what you put in the tank, otherwise you may be off label. So where do we start in our discussion of adjuvants?
First let's define what an adjuvant is. An adjuvant is any additive added to a pesticide used to increase activity and/or modify the physical properties of the spray solution. There are 4 categories of adjuvants: Nonionic Surfactants, which are used as spreading or wetting agents. Oil Based adjuvants which are used for penetrating leaf surfaces and deposition through the canopy. Spreader/ Sticker adjuvants which are needed for deposition and adhering to the leaf surface. And Spray Utilities which are required for pH buffering, deposition and defoaming spray solutions. Some adjuvants are actually part of two or three of these categories. I will start discussing these products in reverse order, starting with Spreader/Stickers.
Spreader/ Stickers are primarily used for deposition and adhering to the leaf surface. Examples of products that we here at Akron use of a spreader/sticker adjuvants would be CoRoN in aerial applications of fungicide. Altohough CoRoN is a nutrientional, it will also has a depositon effect, helping the product get further down in the canopy. Another of the adjuvants that we use that has a sticking capability is Loctite. Loctite is more an oil based adjuvant but it has some sticker properties due to the resins that are in it.
Nonionic surfactants (NIS) are spreading and wetting agents. Basically these products help break the surface tension of the water when it sits on a leaf. These are common adjuvants that have been around for quite a while. Examples of strictly NIS product is Premier 90. They generally do not contain oils, but some of the oil based adjuvants that we use have spreading capabilities. Oil based adjuvants that have spreading capabilities belong to a sub-category called High Surfactant Oil Concentrates (HSOC). This is where products like the aforementioned Loctite and an aerial adjuvant called Cidewinder fit into the adjuvant landscape. In the picture below you will see how Cidewinder will break the surface tension of water when we use a piece of cardboard to represent a leaf surface.
Notice how the drops in front of the bottle of water and the CoRoN mixed with water bead up on the cardboard. When you add Cidewinder the surface tension is broken allowing the water to spread out across the leaf surface. This is very important when you are applying a fungicide as coverage of the plant means better protection.
The next class of adjuvants that I will discuss is the oil based adjuvants. This class of adjuvants are made up of two primary groups Crop Oil Concentrates and Methylated Seed Oil, but there is a sub-class called HSOC which I discussed above. The Crop Oil Concentrates (COC) are made up primarily from a combination of petroleum or vegetable oils and surfactants. Generally they have a higher percentage of oils than surfactants usually 80% or more oil with the rest being some form of a surfactant. HSOC's have a ratio of 60% oil and 40% surfactant. The products that Akron uses in the COC category is just called Crop Oil. It has a low load of surfactant, and a higher rate of oil used to help penetrate the leaf cuticle in get more chemcial in the plant. Examples of HSOC's that Akron uses are Loctite and Cidewinder that we have previously discussed in the above paragraphs.
The other part of the oil based adjuvants that has seen an increase in use the past few years are the Methylated Seed Oils (MSO). When products like Callisto and Laudis were first introduced COC's were recommended by the manufacturer. Now we use MSO's usually with a higher load of surfactants in them to help alleviate some of the leaf burn that we have experienced in the past. Newer products like Sharpen have specified the use of MSO's to help get leaf penetration. When Akron sprays any product containing BASF's Kixor products like Sharpen and Verdict we use an MSO called Firezone. The reason we like Firezone so much is it has a higher KB value than regular MSO's and COC's. KB value is a measurement of how much activity a product has on a plant. If a product has a KB value of 80 it is considered to have herbicial properties. Firezone's KB value is 77, which allows it to penetrate the waxy cuticle of a leaf faster, which in turn results in chemical getting into the plant quicker. Due to it's high KB value Firezone can only be used in a burndown application.
KB Values
In post applications that require a MSO to be used, we will recommend Loctite MSO. As we discussed previously Loctite has oil properties allowing it to penetrate the leaf cuticle. Loctite also contain resins that allows it to have a sticker affect, keeping more product on the leaf surface. And it also has surfactants in it which will help with spreading capability.
Spreader/ Stickers are primarily used for deposition and adhering to the leaf surface. Examples of products that we here at Akron use of a spreader/sticker adjuvants would be CoRoN in aerial applications of fungicide. Altohough CoRoN is a nutrientional, it will also has a depositon effect, helping the product get further down in the canopy. Another of the adjuvants that we use that has a sticking capability is Loctite. Loctite is more an oil based adjuvant but it has some sticker properties due to the resins that are in it.
The final class of adjuvants that I will discuss are what I think of as the most important one, Spray Utilities. This class of adjuvants are what you will use to control the pH of your spray solution. The pH of your spray solution is one of the most critical factors in determining the performance of your herbicide program. Different chemical classes perform better at a certain pH level. For example glyphosate herbicides like to see an optimum pH of around 3.0 to 3. Other products like the HPPD's would like a pH closer to 5. So how do you chose where to build your pH to, I would recommend you try to achieve the pH that is closest to the product that you are wanting to work the best. In other words if you have a spray solution that has glyphosate and Armezon, I would try and achieve a pH of close to 5, as that would enhance the performance of the Armezon which you would need to control some of the tougher broadleaf weeds. In this scenerio the glyphosate is being primarily used to control grass and give just a little help out on the broadleaf weeds. Glyphosate will work at the higher pH, it just isn't optimal. In the chart below I have given some of the pH ranges that are needed for different classes of chemistry:
As you can see for most of the chemistries that you would apply with glyphosate a pH in the upper 4's to the upper 5's would be in the effective range. Now you may ask how do I know what the pH of my water is? The simple answer is that you test it. I would venture to guess that most of us would have hard water, which means you have a pH of 8.5 or greater. This is why we have to add products such as Ammonium Sulfate, N-Tense or other acidifies to lower the pH of the spray solution. Another product that Akron promotes is Blue Max spray solution, this is water that is purified to remove any foreign minerals that might tie up herbicides. Then it is pH adjusted and a compent is added to reduce drift and help with spreading. When using Blue Max water with glyphosate only all you have to do is mix in your glyphosate and go spray. If you are mixing your glyphosate with another chemical you will still need to add any additional adjuvants like oil's or NIS that the label would call for. Many of the adjuvants in the spray utility class contain a drift reduction agent in them already. If they do not you can add a drift reduction agent (DRA) which will fall into one of two categories Guar Gum and Polyacrylamides. Both types of DRA's are effective, but one thing you must not do is mix them. If you start with a Guar Gum in the tank do not supplement it with a Polyacrylamide one. The one advantage that a Guar Gum would have is that it is less suceptible to pump shear. In the past that would not have been a big deal, but with today's spray mixes containing Dicamba, drift reduction is a big deal along with other factors.
Dicamba tolerant soybeans can be a game changer for some people's weed control programs. Monsanto estimates Dicamba tolerant soybeans will be planted on 40% of the soybean acres in the United States. In our area we at Akron feel that number could be closer to 70%. That does not mean that all of those acres will be sprayed with Dicamba products like Engenia, X-tendimax and Fexapan. Many of you would like to save that bullet in your gun and only use it if necessary. But for those of you who are planing on using Dicamba products you need to know the adjuvant requirements are different than anything we have done before. First, we cannot use products containing AMS because they will change the characteristics of the Dicamba molecule and make it more susceptible to drift or volitization. If you are going to spray Dicamba products you must use one of the approved combinations found on each of the products websites. Akron promotes VaporGuard DRA to fulfill the dicamba requirements. It is a water conditionor, NIS, and drift reducing agent. You must also use one of the approved nozzle types found on the websites, but that is a discussion for another newsletter.
In summary, adjuvants play a critical role in your crop production systems. For the past couple of weeks we have been talking about weed control and how it can help maximize yield. The proper adjuvant program will enhance the performance of your weed control. If you use the wrong adjuvant program, weed control will not be as effective and this will allow weeds to rob vital nutrients from your crops. Next week we will discuss fungicides and the role they will play in the system to maximize your crop yields.
News that Caught Our Eye
Last week in this section I talked about factors you need to think about when you are going to grow continuous soybeans. It seems that with the differences in the cost of production between corn and soybeans, people are starting to pay more attention to how to grow more beans. For years many people considered soybeans as just a way to break up the continuous corn and spent most of their time trying to figure out how to raise more corn. I know from personal experience that a lot of my time has been spent on trying to figure out how to grow 300 bushel corn. At the same time I have looked at ways to grow 100 bushel soybeans, but not with the same intensity that I put towards the corn yield goal. This year our plots will be focusing on different ways to grow more soybeans as much as we are looking at how to grow more corn. In my research this week I ran across an article which addressed the concept of how to raise more soybeans. In this article they address some of the same topics like plant your soybeans early, keep them free of weeds and place the proper variety in the proper field. I know many of you are saying this is not new information, I have been trying to do this for years. The parts that they put that was a little different was multiple applications of Nigtrogen. Now I know many of you may have done this in the past and the result might be soybeans that grew taller but did not increase yield that much because the beans lodged. One farmer in Peru, Illinois talked about testing a product that would shorten the distance between the nodes and cause the soybeans to bush out more. I have placed a call into that company and I hope to test some of their products this year and see what they can do. Stay tuned for updates.