Nutrition Management for Mite Infestations

Hi, friends. Welcome to our webinar, where today we are talking about how to manage attrition for spider mites. The narrative that we're all commonly familiar with with spider mites is that they tend to show up in hot and dusty conditions when we have really high temperatures. And often for various parts of the country, when there's a lot of dust in the air that's being blown around. So there's lots of wind stress and in some cases, dust on the leaves. But particularly high temperatures. And for some crops that are being grown in high tunnels, it's not uncommon to have challenges with spider mites in high tunnels as well. So we've become familiar with the idea that there is this environment that is required for spider mites to really flourish and become a serious problem. There's actually a bit more to that story that we've learned in the last couple of years with plant SAP analysis. And the rest of the story is that when we have plants that are in this high temperature environment, they can develop a specific nutritional profile that is kind of the foundational requirement for spider mites to first begin infecting a crop. So it's possible to manage attrition to avoid setting up this environment in the first place or to actually reverse this nutritional profile. Implants. And to allow them to become resistant and no longer provide a food source for the mites, which is really what's happened is that when we change the plant's nutritional profile, they're no longer providing a food source for the mites. So for the webinar today, we're going to share a couple of examples of things that we've observed with some corresponding SAP analysis data. And then we'll describe exactly what's going on with plant nutrition, how we can manage plant nutrition differently to prevent these problems ever showing up in the first place. And then we're going to go straight to Q and A. All right, so foundationally, the first point is that spider mites are. This sentence says that spider mites are attracted to high levels of ammonium in plant SAP. But I would go so far as to say that spider mites are dependent on plants that have high levels of ammonium in plant SAP. If you can succeed in getting the ammonium levels within plant SAP to zero, you will not have spider mites. In fact, if you have trees or plants that already have spider mite, even a severe spider mite infestation in the plant canopy, if you can succeed in bringing the ammonium levels down, the spider mites will disappear. Either they will die if they continue to feed on the plant or they will leave. So it is completely possible to change a plant's susceptibility and resistance to spider mites by changing the ammonium status, the ammonium profile. So this raises lots of interesting questions. How do we have plants that have elevated ammonium levels in the first place and how do we prevent it? Before we get there, I want to give you a couple of examples of what we've looked at. This first example is from an organic corn crop in southwest Kansas in 2015. Here again, we have very high temperature, warm, dusty environment with fairly high winds, constant steady winds. So the crop is under a reasonable amount of stress. This was an organic crop. The crop scout identified spider mites in the crop. This is what they look like pre treatment and following the identification. Almost at the same time that the crop scout had identified, spider mites were moving into the crop very strongly. Even before being aware of this, the grower had already decided to put on a nutritional application in his overhead pivot. This is what the plant SAP analysis looked like in the field. I want to point out these two levels that are highlighted. So for those of you not familiar with SAP analysis, we see here at the top we have a total sugar number that is at 0.9 and 0.8%. And these are actual measured sugars. This is not a brix reading. It doesn't correspond directly to a brix reading. These are actual, if I recall correctly, these are the total non reducing sugars that are being reported with this number. Then you see the second number a little bit further down. And this is ammonium parts per million 429 and 856. And immediately below the ammonium level, we have nitrates 795 and 574. This was back in 2015. We were not yet putting desired values of actual numbers on our SAP analysis, which is now the case today. And then you go down three rows further, you have total nitrogen 1728 and 1799 in the old and the new leaves, respectively. One of the foundational principles of nutrition management for insect resistance. We have observed to manage nutrition such that plants have abundant levels of total nitrogen, but that ammonium levels are below the detection threshold, which is five parts per million. And nitrate levels are also below the detection threshold, which is 20 parts per million. Our goal is to have both ammonium and nitrate show up as zero or none detect on the SAP analysis and and at the same time have high levels of total nitrogen. What this means, in order for this to happen. It means that all the nitrogen that the plant absorbs from the soil or from the atmosphere in any form, whether it's in ammonium form or nitrate form, or urea form, or an amino sugar form, or amino acids, is rapidly converted to proteins and peptides, and it does not remain in the plant SAP in either the nitrate or the ammonium form, which this measuring technique is picking up and reporting separately from total nitrogen. So we know that anytime. I'm very confident if we have crops that are in an environment, in a warm environment, and the crop is a crop type that is susceptible to spider mites, when we cross the threshold of 400 parts per million, if you have greater than 400 parts per million ammonium in plant SAP, There is greater than a 90% probability that you will have spider mites already present in your crop. If you can get that level down to a none detect, spider mites will cease to be a problem. Shortly after the crop scouter, I think it was almost at the same time that the crop scout identified the spider mites were moving in. This farmer put on an application of these nutrients through his pivot, Based on a historical SAP analysis that had been taken a couple of weeks earlier. And when they were putting on these products, they were running the pivot around the circle as rapidly as they could to put on the least amount of water, which I think is 10,000 gallons per acre, if I recall correctly, and it might be less than that, I'm not completely certain of that anymore. But the smallest amount of water that they could put on with the pivot, and it took the pivot 48 hours to make the entire circle. So 48 hours after the application, the crop scout came back and looked at it again. And they observed that right where they started the circle first and the product had been first applied, the spider mites were dead. And at the end of the circle, where the product had just been applied a few hours previously, that was not yet the case. So it seemed to take about 48 hours for the effect to become observable and to actually see the dead spider mites in the field, so that the spider mites disappeared and they did not reappear for the rest of the growing season. It ended up producing a yield of 215 bushels per acre of organic corn. And the other interesting aspect was that, in addition, there were also no corn earworm, There were no corn borer, There was no other insect pressure on this crop at all. An example on a different crop was peaches in California. So we have Mites showing up, we have ammonium levels at 176 part per million on the new leaves and 93 on the old leaves. And again, you can see that the sugar levels, this is actually interesting. The total sugar levels on this SAP analysis show as being higher than common, which is a bit of an anomaly. Normally when we see the presence of spider mice in these high leaf temperatures, we see sugar content in the SAP analysis being lower, significantly lower in many cases, when we have high ammonium levels, this is what the same crop looked like in 2019 when no spider mites were present. We have ammonium levels 92 and 53. So the ammonium levels are, they're still present. We would like for these to be at zero. But even at these lower levels and similar weather conditions, similar climactic conditions, we did not have spider mites showing up. So when we consider ammonium within the crop, the questions that we need to ask are what occurs for this ammonium to show up in the first place? And then once it is present, how can we manage it and how can we reverse it? So the challenge, as I mentioned earlier, is that plants, ammonium is coming from somewhere faster than the plants can convert it to complete proteins. So the three common conditions that can result in plants accumulating ammonium are when you have excessive nitrogen applications, not just in the ammonium form, but also urea, for example, or even nitrate, depending on soil conditions. So if there's excessive fertilizer, nitrogen applications, more than the plant can metabolize, that can result in an accumulation of ammonium. The second possibility is when you have saturated soils or very wet soils. And the third is when you have high leaf temperatures. And I would wish to emphasize the focus on leaf temperature. I'm not talking about air temperature. High air temperatures contribute to high leaf temperatures for sure, but there is not a direct linear correlation. The degree of plant health and the degree of photosynthetic integrity and lipid production can have a significant impact on the plant's capacity to cool itself. So the healthier a plant becomes, it can actually remain cooler in very warm environments, in very warm conditions. So the healthier a crop becomes, the cooler the leaf temperature when compared to an unhealthy plant in the exact same air temperature. So, so the focus, the emphasis needs to be that we need to be managing and measuring leaf temperature rather than, or thinking about leaf temperature rather than air temperature. So when we look at each of these three, the first consideration, application of more nitrogen than the plant can metabolize. So if we're applying nitrogen fertilizers, we need to spoon feed only what the crop requires and not put on large quantities at any one moment in time, because anytime we put on very large quantities of nitrogen, plants absorb it fairly readily. And if they absorb more nitrogen than they can convert, because perhaps they don't have enough sulfur, they don't have enough other minerals to fuel the conversion process that will result in the accumulation of ammonium as well as the accumulation of nitrate in the plant that sets the stage for spider mites to really flourish. The second possibility is that when you have soils that are wet, particularly soils that are saturated, this will convert the nitrogen that is present in the soil profile that might have been historically applied. It can be organic nitrogen from compost. Any form of historical nitrogen applications, or just the nitrogen that exists natively in the soil associated with organic matter, will convert to the ammonium form, because the ammonium form is the reduced form of mineral nitrogen. So we have this very reduced environment. For those of you familiar with the conversations I've been having the last few years about reduction versus oxidation, when you have a reduced soil that is saturated, you have this accumulation of ammonium or conversion to ammonium. And the majority of the nitrogen in the soil will be in the ammonium form, which is why rice and blueberries are adapted to only absorb ammonium and they can't absorb nitrate because they are natively adapted to thriving in this saturated environment. This is not likely to be significant for growers who are irrigating a lot of. But it can have. It is possible with irrigation, particularly with flood irrigation, to have a short term snap effect. So if you're using flood irrigation, you can convert the majority of the nitrogen from applied fertilizer into ammonium and have it have an ammonium flush that maybe lasts for only three to five days within the plant, but that three to five day window can be long enough for the plant to accumulate enough ammonium to lead to spider mite susceptibility. It's a common practice for some growers to underneath tree fruit that we've worked with, in particular nuts and so forth to broadcast or to band fertilizer along the row and then to furrow, irrigate. And the fertilizer band would be placed at the side of the furrow. And when this happens, that means that those nutrients are now solubilized, obviously. But the nitrogen that is present, even if it's in the nitrate form, if the soil is warm, we have vigorous biology and we have an environment that is temporarily saturated, even for a 24 to 48 hour period, it will convert the majority of the applied nitrogen into the ammonium form. So you can actually temporarily create a strong surge of ammonium. That is a big deal to be aware of. Then the third environmental consideration, a third factor that can contribute to high ammonium, is high leaf temperature. When we have high leaf temperatures, plants switch from being photosynthesis dominated to photorespiration dominated. Their primary processes switch. So the question is, what defines a high leaf temperature? And I'm going purely from memory here, this is worth double checking and verifying. But if I Recall correctly, for C3 photosynthetic pathway plants, which is most of our fruit and vegetable crops, and all the crops mostly except the warm season grasses, these plants, the threshold is a leaf temperature of 78 degrees Fahrenheit. For C4 plants, such as corn and warm season grasses, the threshold, if I recall correctly, is 86 degrees Fahrenheit. So at these thresholds, plants will switch from being photosynthesis dominant to photorespiration dominant. And this is a really big deal. The reason it's such a big deal is because during photosynthesis, when the plants are photosynthesizing, they're absorbing water from the soil, collecting sunlight and carbon dioxide from the air, they're producing sugars. And during the photosynthesis process, the plant is getting the majority of its energy from sugars. During photorespiration, when the plant becomes photorespiration dominant, then the key process is that the plant needs to cool itself. And so to cool itself, it begins using the majority of the water flow as a cooling mechanism and begins respiring rather than using the water for photorespiration. The result is that when this happens, sugar production and photosynthesis drops, so your sugar production goes down. Which is why I was pointing out on the SAP analysis that often when we have high ammonium levels because of these high temperature environments, sugar levels in the leaf actually drop as a result of a slowdown of photosynthesis. And yet this plant desires to sustain itself. It doesn't want to lose fruit, it wants to successfully reproduce. And in order to sustain itself, to keep from going backward, it has to get energy from somewhere. And so if it does not get energy from sugars, it begins getting energy from proteins that it has formed in the past. So during this photorespiration dominant period, plants sustain themselves by extracting energy and breaking down proteins. This process is called protein catabolism. And so during this protein catabolism process, they get energy from proteins, they break them down into their constituent peptides then to amino acids. And the final breakdown product of protein catabolism is ammonium. So plants can actually accumulate ammonium within the leaf that did not exist previously as ammonium simply as a result of a high temperature environment. And actually we didn't put this point into the deck, but it's worth mentioning that plants, when they absorb ammonium from the soil, then the ammonium is converted to amino acids and to amine forms of nitrogen in the root system, so that conversion process doesn't happen in the leaves. So optimally for the plant, from a overall plant health perspective. So ideally, ammonium that gets absorbed from the soil is converted to amino forms of nitrogen and organic forms of nitrogen in the root system and then moves up into the upper parts of the plant already as a constituent of amino acids, peptides and proteins. That doesn't happen when we over apply a fertilizer or when we have a flush of available ammonium from the soil. We can overwhelm the root system's capacity to convert all the ammonium to amino acids and so forth. So ideally, the soil should never deliver such a large flush of nitrogen at one moment in time that it overwhelms the root system's capacity to convert it. And if we're successful in accomplishing that, we will never get these high ammonium levels in the plant SAP as a result of a fertilizer application. So ammonium should never come from the root system upward. So if we're successful in doing this, when we do a SAP analysis, and the SAP analysis shows that we have elevated ammonium levels, that means the ammonium didn't come from the root system, it came, it was developed in the leaf as a result of protein breakdown. So now the next question becomes, well, it is optimal for a plant to convert ammonium the root system. How do you manage the conversion of ammonium back to amino acids and amino sugars in the aerial parts of the plant, in the canopy and the leaves? And it is possible, plants do have the mechanism to do this. It's not as efficient as doing it in the root system, but there is, there are nutritional requirements that have to be in place in order for this to happen and to work. Well, we'll get to those in just a moment. So when we look at preventing mite infestations, there's really two foundational factors that we need to manage in addition to nutrition. The first is that we need to reduce leaf temperatures and keep leaf temperatures cool. And I'll elaborate on that in just a bit. The second point is that we need to manage nitrogen applications with precision and only apply what the crop needs and no more. When we apply excessive nitrogen, we are asking for mite infestations. So when we consider managing leaf temperatures, the key characteristic is that plant leaves can be cooled much more efficiently when we have this glossy waxy layer on the leaf surface as a result of increasing lipid synthesis and lipid formation within the plants. This is something that I've spoken about frequently in the past. If you want to dig into this a bit more deeply, I would suggest looking at our previous webinars on the Plant Health Pyramid. What I'm describing here is that when plants get to level three of the plant Health Pyramid, they begin producing an abundance, a surplus of lipids, more than the baseline that's required to sustain themselves for and to produce produce cell membranes. So when they produce this abundance of lipids, this layer of waxes and oils begins accumulating on the leaf surface. And we can observe this visually by the glossy waxy sheen that is present on the leaf surface. And I know from a lot of field experience and measurement that when plants and leaves have this glossy, waxy sheen, they remain much cooler, the leaf temperature is much cooler, and they warm up much more slowly than unhealthy plants, even in the same air temperature. I have some ideas and hypothesis about why that might be the case, but I've never sought to identify exactly why this is happening. I suspect that we know that waxes and oils are very efficient conductors. And I suspect that during the respiration, the photorespiration process, being very strong heat conductors, allows the plant to cool itself much more rapidly. And I also suspect possibly the waxes on the leaf surface reflect heat much better as well. So I don't know which or if either of those can be correct. I think it's something worth looking into and trying to understand better. But from a practical experiential perspective, we know it to be the case that plants that have this glossy, waxy leaf surface can easily be 5 to 10 degrees Fahrenheit cooler than unhealthy plants in the exact same environment. So that can be a very significant difference. That can actually mean a really big difference, because now these plants also require less water to stay hydrated, essentially and to continue the photosynthesis process. So plants that have these higher energy levels, that produce lots of lipids actually continue to produce higher yields and they're continuing to photosynthesize in these high air temperature environments and applying minimal amounts of nitrogen, as indicated by SAP analysis. I've Already emphasized this point a couple of times. Only apply what the crop needs when it needs it. And what we have observed with SAP analysis is that there are two nutrients which are consistently over applied in much larger quantities than the crop actually requires. And those are nitrogen and potassium. There are many growers who can safely reduce nitrogen applications by upwards of 40% with no decrease in crop productivity. If they simply time those nitrogen applications at the moment when the crop needs them and not giving them and spoon feed them through the season rather than giving them all one shot at once, it creates a lot of susceptibility challenges. So the nutrients which are required to convert ammonium in the leaf back into proteins following the catabolism process or following the overwhelm of the root system. Whatever is happening is that you need to have adequate carbohydrates, magnesium, sulfur, molybdenum, and in some soils, in some situations, you also need to address nickel. We've found that with the first four elements, carbohydrates, magnesium, sulfur and molybdenum, putting on a foliar application of those four nutrients will convert the ammonium that shows up in a SAP analysis back into complete proteins in a matter of 24 to 48 hours in about 80% of the cases, 80% of the time, and maybe a bit more than that. But occasionally we don't get the response that we expect. And we. I've worked with some colleagues internationally who have done some homework on this as well. And we have some challenges here in North America working with nickel because from a regulatory perspective it's consistent considered to be a heavy metal and it's not something that we can make recommendations to apply to a crop. For most crops, pecans are an exception. There's a few crops that are an exception, but for most crops we can't make this recommendation because it's considered to be a heavy metal and the quantities that are required are extremely small. We're talking about in the neighborhood of 5 to 10 grams per acre of actual nickel. But for the most part it's been difficult for us to access products or develop products that contain nickel that we can make recommendations for given the current regulatory framework. So that is something to keep in mind if you put on this application and don't get the response that you're expecting, which from our experience doesn't happen often, but it does happen occasionally. And that might be the reason why your soils might not have enough nickel. The products that we have put together, which contain these nutrients and produce this spider mite resistance response that we're looking for as a result of changing ammonium levels and changing the plant's nitrogen profile is fotomag, rejuvenate and sea stem. So also wanted to point out an upcoming issue event that we have coming up in August, an online course that is going to be specifically focused on California agriculture and some of the topics and things that we need to be concerned with with dry land, irrigated fruit and vegetable production in these environments. So would love to see you there. If you have any follow up questions or want to dig a bit more deeply into understanding how to put these protocols together for your operation, specifically for not just for spider mites but for any other pests that you're dealing with, feel free to reach out to the Advancing EcoAgriculture team at this email address infovancingecoag.com they would love to hear from you and connect with you. So I see quite a number of questions have been coming in. I want to say thank you for that. I really enjoy them. So Question from Dan Pavitch how do you determine whether it's too hot to make an application? Foliar application so the ideal is to put on foliar applications when leaf temperatures are below the thresholds that I mentioned 78 degrees Fahrenheit and 86 degrees Fahrenheit for C3 and C4 photosynthetic pathway plants respectively. And the easiest way to measure that is just to use an infrared thermometer that is a point and shoot thermometer. You can easily measure leaf temperature of the canopy with those. Follow up question from Dan Dr. Reams recommended applying a carbohydrate with your nitrogen. Companies like Conquint Ag disparage that practice. Do you have a preference? I prefer not to be asked about other companies practices but for our own recommendations. We consistently apply carbohydrates with our nitrogen sources both to the leaf and to the soil because our desire is to particularly in the case of soil applications, we want to stimulate biology to convert all of the applied nitrogen to amino sugars as rapidly as possible because we gain a lot of plant health and soil health benefits from that conversion. Question from Nathan Lindar Are there any irrigation systems that don't cause ammonia conversion from saturation? It's not the irrigation that is the.