The Role of Micronutrients in Crop Health and Disease Resistance

Good afternoon friends, and welcome to our webinar on the role of micronutrients in plant health, disease resistance and immunity. This is a topic that I am very excited to speak about. We believe that it is possible for plants to be completely resistant to diseases and insects based on how we manage plant nutrition, particularly these trace minerals and these micronutrients. And this is a topic that generally we have to be very careful speaking about how products, different products, produce disease and insect resistance. That's not really a safe conversation from a regulatory perspective. And so the scope of the conversation today, instead of speaking about products, we will be speaking about the roles of specific trace minerals. And this is a topic that I believe is very important and very timely and we'll be providing a lot of references, a lot of more additional information that you can follow up on and look at on your own. So I'm going to share some thoughts about how we think about managing these trace minerals from a management perspective. Some of the key things you need to think about and some of the diseases that you can produce resistance to when you manage these trace minerals. Well, provide you with some references. There are many times when growers or consultants will call and say, hey, we have a problem with this disease or this crop. Can you help us find a solution for it? What can we do about it? And there are two tools that I use very consistently and they're my first go to tools when I get asked that question. And the first, the first that I will look at is this book titled Mineral Nutrition and Plant Disease and co edited by Lawrence Datnoff, Wade Elmer and Don Huber, sometimes referred to as the published by the American Society of Phytopathology. And it's an incredible reference. I'll be sharing a lot of references from this book through the course of the conversation today. But if you really have an interest and a desire to produce disease and insect resistance, particularly in this case disease resistance based on how you manage nutrition, this book is a must have go to reference. It is very foundational to understanding how diseases or how plant nutrition, how trace mineral nutrition influences a plant's capacity to resist different pathogens. My second go to tool is Google Scholar with a very simple and very specific search. First I identify the specific organism that I want to understand well, such as a specific species of Xanthomonas or Pseudomonas or Rhizoctonia. And then I will do a search for nutritional requirements of and the specific name of the organism. Very often, not always, but often with some digging and some searching we'll be able to find that a specific organism has requirements for a specific amino acid profile or specific carbohydrate profile that we can then link the amino acid and the carbohydrate profile to and identify that whatever is either present in high concentrations or is absent would lead us to look at certain enzyme pathways and certain enzyme cofactors that we can then correlate back to specific nutritional profiles and understand what is happening and why we have plants that have a given nutritional profile that then results in given disease and insect susceptibility. So those are two resources that I would very highly recommend you take a look at if you want to dig deeper into this topic. So I believe that managing these micronutrients and trace minerals is critical. It's the foundational piece if you want to develop resistance to various diseases and different insect pests. This is the foundational entry point. This is not where we end up. This is where we have to begin. And so I'll be reviewing seven different of the primary micronutrients. And we know today that there are many more than these seven primary elements that are also considered beneficial from a disease and insect resistance perspective. From an overall plant health perspective, there are now an increasing number of micronutrients that are considered to be beneficial, though not essential. Examples would be lanthanum and silver and iodine, nickel and quite a, quite a long list. I think there's now an additional list of 12 or 15 in addition to these that are on the screen that are considered to be beneficial to plant development and plant growth. So we're going to be looking at these seven primary elements. Many these elements, you're already. Most growers are already measuring these and monitoring them. It's possible that you may not be measuring cobalt molybdenum with, if you're not using SAP analysis or if you're not using soil analysis. And you definitely need to. With what we understand about these trace minerals and the impact they have on yields and on quality, we need to begin managing and measuring them. They're equally as important and have as significant an impact on overall crop development as any of the other trace minerals on this list in their own way. For first, we're going to look at boron. When we think about managing boron from an agronomic perspective of how we, how it influences a crop and the crop characteristics that we need to manage for, there's two pieces that we think about. The first is that boron increases sugar translocation to the sugar sinks. It increases the speed and it also guides where the sugar goes. This is a very useful characteristic when a crop is approaching maturity. And we want to speed up maturity in the last two weeks or three weeks before senescence and before final maturity, we can help the plant move a lot of sugars into the seed or into the fruit. So if we're producing small grains, or if we're producing onions or tomatoes or almost whatever case the crop might be, when we put on a boron application the last two weeks before harvest, it will really speed up sugar flow and nutrient flow into the fruit and into the sugar sink very quickly, which can result obviously in some substantial yield gains. And then the second consideration with boron is that it increases calcium absorption from the soil and also it increases calcium mobility within the plant. It allows the calcium to move when absorbed from the root system being transported through the xylem. It allows calcium to move into the fruit and into the new growth much more easily. And this is very important because often during summer months, when we get into higher temperature periods, boron, excuse me, calcium, tends to not move as easily in the plant anymore. It tends to become sluggish. It follows the transpiration stream, and the water stream will tend to settle out and accumulate in the lower, older leaves. When we have an abundance of boron present, it will move. It will not remain in the lower, older leaves and accumulate there, but it will instead quickly continue to be transported into the fruit, which is a really big deal if we're dealing with fruit calcium related physiological disorders. Boron specifically is known to increase plant resistance to Rhizoctonia, verticillium and Fusarium. These are some of the diseases that we think about managing with boron applications and is also effective against some viruses. If you want to dig a bit more deeply into this, this is a table from the book that I referenced earlier that describes how the presence or applications of boron either reduced or increased the presence of these various diseases. When we look at cobalt, cobalt also has two very important management considerations. The first is that it can delay maturity and delay ripening because it reduces or in some cases can even inhibit the formation of ethylene. Plant stress ethylene and ethylene that is also produced from maturing seeds. So if we have. This can be a very interesting tool that is the counterpoint of boron. Boron can speed up maturity. Cobalt can slow it down. So if we have a crop, let's say, such as green beans, and we want to slow down the maturity of the first set so that we can also Harvest the third set when we're going through with machine harvest, so that we get the first, second, and third set all at one time. One of the tools that we can use to accomplish that is applications of cobalt, because cobalt will slow down senescence, slow down maturity of that first set, and allow the plant to begin sizing the third set very effectively. Secondly, cobalt is also required as an enzyme cofactor in the growing root tips to synthesize cytokinins. So we find that when plants have adequate levels of cobalt, we have much higher levels of cytokinin production and very tightly spaced internodes on the upper parts of the plant and a lot of branching. So very strong reproduction that is connected to having adequate cobalt present in the root system. When we look at copper, the one management characteristic that we think of when thinking about copper is that it provides cell elasticity and stem elasticity and fruit skin elasticity. So if we have challenges with fruit cracking and splitting, such as with grape tomatoes or with cherries or the bark of some plants, having adequate levels of copper present will give us additional elasticity and can help significantly reduce splitting and cracking. In addition, when we have challenges with fruit, or, excuse me, with plants that want to break when they have a lot of wind stress or storm stress, they don't bend very well. They just snap off. If we have challenges with lodging, such as on corn and small grains and so forth, having adequate levels of copper gives plant stems a tremendous amount of flexibility that allows them to bend. And after the wind is over, they can stand right back up again. And this is because of the effect that it has on lignification, etc. Within the stem. So having high levels of copper from a management perspective gives us a lot of flexibility and strength. You can easily test this and observe this in the field. If you're walking through a field with crops that have branches that branch off from the main stem, let's use brassicas as an example, such as broccoli or cauliflower. You can walk through a field occasionally and the leaf petioles will be very brittle. They snap very easily, they don't bend, particularly on a cool morning. And that is a certain indicator of not having adequate levels of copper. When we look at the list of diseases that copper provides resistance to, it's a very extensive list. Bacterial canker, all types of bacterial diseases. Bacterial canker, bacterial speck, bacterial spot, bacterial wilt on a number of different crops. And when you stop to think about it, one of the mainstream management tactics for managing bacterial infections in crops is with applications of copper, but in this case applications of copper as a bactericide on the outside of the leaf or on the outside of plant. And the management strategy that we should consider instead of having copper on the outside the leaf, is actually to get copper into the leaf by using copper nutrition products. And then when we have copper inside the leaf now the resistance becomes inherent within the plant and we don't have to constantly apply bactericides that decimate the microbial population on the plant leaf surface and within the soil. So we're using copper in a different form and with a different approach, a different thought process to produce inherent resistance inside the plant. So quite a long list of diseases. And then of course, this list is just. I've selected the highlights from the list that was provided in the book I referenced earlier, Mineral nutrition and plant disease. And this is the second page. And there's also additional references, the text that are not listed on the table. So there's quite an extensive list of diseases that these minerals can produce resistance to. When we look at iron from a crop management perspective, there are two key considerations for managing iron. The first is that iron is required to assemble chlorophyll. It is not a part of the chlorophyll molecule, but it's required to assemble chlorophyll. And when we have high levels of iron, we have a plant that has this dark green, lush appearance because of high chlorophyll levels. And inversely, when we don't have enough iron, we will have very pale colored plants. And then secondly, iron, completely distinct from its requirements or its presence being needed to assemble chlorophyll, can also tremendously increase photosynthetic efficiency through a number of different mechanisms. One of the mechanisms is that iron is the, is one of the elements that is needed to form all of the carotenoids, such as astaxanthin, zeaxanthin, etc. And the reason these carotenoids are important is because each of them collects a small portion of visible of the visible light spectrum. And together, when you have this array of seven or eight different carotenoids, they cover the entire spectrum and they absorb and collect photons and feed photons into chlorophyll. So you have the effect that when you have adequate levels of iron, you can actually absorb as much as 7 to 8 times wider bandwidth of the visible light spectrum and feed a lot more photons into chlorophyll. And the effect is that you can tremendously increase photosynthesis. That's just one of several mechanisms by which iron impacts photosynthetic efficiency. When we look at manganese levels that there are two important considerations for three important management considerations for when we think about how to manage manganese. The first is that manganese is essential for water hydrolysis, which is the first step in the photosynthesis process. So when plants absorb water from the soil and they move that water up into the leaves, the very first step is that water molecule H2O gets split into H and OH hydrogen and hydroxyl ions. That splitting of the water molecule is referred to as water hydrolysis. And this process is completely dependent on manganese. This is very important realization because it means that even when plants have adequate water and they have enough sunlight and they have enough carbon dioxide, if they are low in manganese, none of the rest matters because that can still slow down the photosynthesis process. That becomes the bottleneck, that becomes the limiting factor. The second consideration for managing manganese is that it is essential to regulate potassium absorption from the soil and potassium movement within the plant through the various sugar sinks into the fruit, etc. And the third important consideration is that manganese, along with some other elements such as iron and copper and cobalt, need to be absorbed by the plant in the reduced form in order to be biologically active and physiologically active within the crop itself, within the plant itself. Again, when we look at the diseases that manganese produces plant resistance to, it's a fairly extensive list. Phytophthora anthracnose, Rhizoctonia fasarium, late blight, early blight, Downy and powdery mildew bacterial speck. I selected these diseases to highlight because they are for many crops, the diseases that are correlated to manganese and to copper cover a significant array of the most economically damaging diseases for a lot of different crops. There are certainly some outliers, but this covers a very significant spectrum of economically impactful diseases. Here are the pages of references for the impacts of manganese, which you can go back and use as a reference when we look at molybdenum. Molybdenum is needed for two important functions. One is that it is the enzyme cofactor for the nitrate reductase enzyme to convert nitrates to amino acids within the plant within the plant leaves. And secondly, molybdenum is also needed for the nitrogenase enzyme complex that is found in organisms that have a symbiotic relationship with plant roots to fix nitrogen. So these would be Azodobacter, Azospirillum and All the rhizobium that are used for legumes, all these various Rhizobium bacteria require molybdenum in order to fix nitrogen. And when molybdenum is absent, we have, in the case of rhizobium nodules, we can see rhizobium nodules that have a white or gray appearance on the inside. And when molybdenum is present, they turn pink or reddish colored on the inside and they become much more functional, actually fixing nitrogen as well as the population. The presence of these organisms will increase tremendously when molybdenum is present as well. Molybdenum can also increase plant resistance to a number of these different diseases. Verticillium and angular leaf spot, I think is a very interesting one. The directly connected angular leaf spot, as well as Xanthomonas viruses. And it also will inhibit nematode infections. And in addition, this is not yet in the peer reviewed literature that I'm aware of, but from field observation and experience, we've also observed that molybdenum is very important to manage all of the bacterial infections that infect the plant's vascular tissue. So these would be diseases such as Gossis wilt on corn, sudden death syndrome on soybeans, citrus greening, Pierce's disease on grapes, and crown gall on walnuts and nut trees. So anytime we have bacteria that invade the vascular tissue of a plant, the presence of those organisms can be significantly reduced when we have adequate levels of molybdenum. And also when we think about viruses, the presence of various mosaic viruses, and there's obviously a broad array of viruses that are important. I've recently learned that the presence of molybdenum can have a significant impact on reducing or preventing viral expression on a crop. And this is actually also shows up the very first paragraph in the book that I referenced. Molybdenum, like other heavy metals, deactivates viruses by denaturing their protein coat 1967. So that raises the question, when we have viruses present in a crop, how would that crop expression change when we ensure that it has adequate levels of molybdenum? Also want to speak about zinc. The key management consideration that we look at when managing zinc is leaf size and uniform shape. So generally when we have adequate or generous supplies of zinc, we will have larger, wider leaves and leaf shape ratio will change, where we will generally tend to have wider leaves that are shorter in ratio to each other. But the other important consideration is looking at the Uniformity of where the leaf joins the stem, the petiole. So if those are offset, if one leaf, one side of the leaf attaches to the petiole, separated from the other side of the leaf by a quarter of an inch or a half an inch, that dissimilarity a reflection of low zinc levels and a plant not having adequate zinc. Zinc also increases plant resistance to a number of different diseases. Again, it's connected to Rhizoctonia and Fusarium scab, some viruses. And the one point that I did find interesting in a review of the literature is that it also reduces the presence of aflatoxins in grain. And again, we have an entire page of references to the impact of zinc. Two pages. Actually. One of the important considerations Whenever we speak about trace minerals, I'm often asked the question, how can we most effectively apply trace minerals? Can we use trace mineral sulfates such as zinc and manganese and copper sulfate as a source of nutrients? Should we look at synthetic chelates such as edtase, manganese, edta, chelate? Should we look at eddha, which is also another synthetic chelation agent commonly used for iron? And since we've started using plant SAP analysis in 2011, one piece has become really clear about managing these trace minerals. It is obvious that plants absorb the organic acid and the amino acid chelates far more effectively and far more efficiently than they do the synthetic chelates. If we compare a manganese application that is in the form of EDTA versus an organic acid chelate, the organic acid chelate always shows significantly greater presence of manganese in the SAP analysis than the EDTA will. And the same is true of iron and EDDHA or edta. So in general, we find that the organic acid and amino acid chelates tend to produce a much bigger crop response and actually show up in the plant on plant SAP analysis more effectively than the other forms that are available. So we've actually, as a result of starting to use SAP analysis, after using it for several years and observing the differences in absorption of various trace minerals, we set out to develop a line of trace minerals that were very effectively absorbed by plants, which resulted in our production of the rebound micronutrient line, which we have available. So would love to have you use those materials and actually measure and see how they perform and work on your crops when you measure them using SAP analysis. So that wraps up the presentation. The thoughts that I wanted to share. If you have any questions, I really enjoy the interaction. If you want to send those through, I would really enjoy that. There's some questions that have come through already. So we're just going to jump right in. First question comes through from Andy Harper. As a strawberry grower, botrytis has been prevalent. What micronutrient will be the most effective? Well, Andy, I don't know the answer to that right off the top of my head, but it's in here. I'm positive that it is. The reality is this is a reference book and yes, it's a science book, it's scientific material. It's used to teach phytopathology at many universities today. But the reality is, at a cost of $90 or $100, I'm not sure exactly what it is available for on Amazon right now, but at a cost of $100, this is a tool that you cannot afford not to have on your shelf. It is really that simple. You compare the cost of that $100 to the cost of a fungicide application or applying the wrong products at the wrong time, and you really can't afford not to have it. So as an example, I'm just going to quickly look up the question that you asked about botrytis on strawberries and we'll see what I can find. Botrytis, there are about 15 different references, 16, 17 different references. So I'm going to make it really quick. Page 33 and 34. Botrytis and Strawberries is correlated to the applications of excess of nitrogen. The first thing that shows up. And there's again, there's a dozen different references here. So you can probably. It'll. If you follow up all those references, you'll likely discover that you have. When you have the presence of botrytis, it'll correlate to an excess of nitrogen, perhaps a deficiency of manganese and a deficiency of boron and excess of potassium. I don't know for certain. I'm just making up a hypothetical example. But because of the number of references that are listed, you're likely to find that there is a clear pattern of high levels of some nutrients will tend to promote it and other nutrients, the presence of other nutrients will tend to suppress it. So it's a very useful resource that you should follow up on. Question here from Kenneth Peters. Hi, Kenneth, can I repeat what I said about zinc deficiency while looking at the petioles? So when you want to have perfect symmetry where the outside edge of the leaf join the stem, so they should come together at exactly the same location. If you have a leaf where one side joins the petiole here and the other side is separated by a Half an inch or an inch or by any distance for that matter. So when you have that discrepancy in where the leaf joins the stem and it's not perfectly symmetrical, it needs to be perfectly symmetrical. If it is not symmetrical, that is an indicator of a zinc deficiency. And there are a few crops that genetically tend to have more, tend to lack symmetry. And there are a few tomato varieties that will do this very well, particularly on the leaves that are not at the tip of the outer leaf. So some of the side leaves may lack that symmetry, but in general for most crops, you want to see that perfect symmetry between where the two sides of the leaf join together at the stem. A question from Thomas Jarrett. How would you manage the potential of over fertilizing micronutrients? The answer, Thomas, is very simple. You do not guess, you measure. You measure using a plant SAP analysis. And when you use plant SAP analysis, then you can know exactly where your crops are, what the desired levels are, and how much you need to apply to get the result that you're looking for. It is certainly possible to produce excesses of some of these trace minerals very easily, some more easily than others. And so we need to be very careful to avoid over applications. Question here from Laron. Is there any correlation or research that connects the moon phase to the timing of specific nutritional applications? You asked the most fascinating questions. There is some research and we do use this occasionally when we are able to here at aea. And right now it's escaping my memory, which is which. But we've learned from measuring again from SAP analysis and from measuring nutrient absorption consistently throughout entire month or multiple months or entire growing period, growing season for that matter. We've learned that there is one week out of the four week lunar cycle where plants absorb nutrients exceptionally well. They absorb a tremendous amount of nutrition. In one week out of the four, there are two weeks which are average and one week that is exceptionally poor. In the week where nutrient application or nutrient absorption is very poor, it's probably would be ideal to not apply foliar applications or irrigation applications or perhaps to reduce rate at that moment in time. Or if we have a severe deficiency and we have to balance that and manage that, we may need to just understand that we may need to actually apply a larger rate to get the equivalent crop response. Question, can manganese stop red coloring on Granny Smith apples? The answer is yes, it can. When? If you apply excessive manganese. Again, this goes back to the point about testing. If you apply excessive manganese, then the manganese excess will limit potassium movement and therefore sugar movement into the fruit and will slow down coloring. So it's actually the fact that the high levels of manganese are limiting potassium flow. And you can reduce color on Granny Smith or on any other apple variety for that matter, or for any other fruit you can, you can limit coloring. Question from Darren Greenfield. When a disease such as powdery mildew appears, can the applications of a rebound copper foliar slow down or prevent the spreading of the disease? The answer is when you address the trace minerals that are missing, that are not in adequate supply, that are leading to increased susceptibility, and you do it at a generous enough application rate, early enough, then the answer is, yes, you can stop the disease and you can prevent it spreading. And in many cases you can actually reverse it. And of course, reversing it depends on the disease and the damage that it has already done to the tree's vascular tissue or to the leaf vascular tissue, etc. Some diseases you can't effectively reverse because they have done too much damage already. But for a number of diseases such as bacterial canker, bacterial speck, bacterial spot, we've actually observed, I've actually observed and experienced a broad different array of diseases where growers applied trace mineral foliars, usually in combination. Generally, it was not just one trace mineral. It would be a combination of zinc and manganese and copper and boron, whatever was indicated, preferably based on SAP analysis, but sometimes based on experience, and they were able to completely stop a disease that had already begun expressing itself and was becoming very, very virulent. So, yes, it is possible to use plant nutrition to prevent the spread of disease. Question from Cameron Morgan. Hi Cameron, do you see any common nutritional themes with flea beetle attacks on nursery stock? Yes. When you look at the diagram that we put together with a plant health pyramid, flea beetles would show up on level two. When plants are not producing complete proteins and you have high levels of nitrates and soluble amino acids in the plant SAP, which is generally an indicator of inadequate levels of either magnesium or sulfur or molybdenum or some combination of all three of those. Anthony Granatelli. Hi, Anthony, glad to see you here. Of the minerals discussed today, which minerals have better correlations between SAP analysis and soil levels? I would say the only two. There are only two, which actually, I'll expand that to three. There are three which somewhat correlate between soil and SAP analysis, and those are molybdenum and boron because they are anions and do not attach to the soil's cation. Exchange capacity, soil colloids. And the third is zinc, because zinc is not required to be absorbed or doesn't have different oxidation states and can be fairly readily absorbed from the soil profile. All of the other metals, manganese, copper, cobalt and iron. There is no correlation between levels in the soil and absorption by the plant. It's a very good question. Anthony Malcolm asked the question, organic acid chelates. Is fulvic acid the best chelator? Can the minerals be combined into a nutritional foliar spray stack? So, yes, to answer the second question first, you can combine all these different trace minerals into a single foliar application. There are many organic acid chelates which are effective. Fulvic acid is good, but there are also others such as citric acid and a number of different organic acetic acid and carbonic acid, lignosulfinates, etc. There's a number of different materials that are effective chelators and can move nutrients into the plants very effectively. Another question. We have hard water with high iron. What can we do? It's very simple. You change water or you use reverse osmosis. So you can either use rainwater or you can use a reverse osmosis system. There's nothing else that you can do effectively when you have hard water and high iron. And I'm speaking specifically to the use of that water as a foliar application, not so much for irrigation, although it's also a negative there. Anthony asked the second question. Which minerals are more likely to cause problems if provided in excess? That's a very interesting question, Anthony. Interestingly enough, for the trace minerals such as molybdenum and boron, the excesses, I'm sure if you were to get high enough, you could have an excess that would cause problems. But generally the excess, when those nutrients become those trace mineral anions become very high. The only problem from a plant health and growth perspective is that they cause functional deficiencies of the nutrients that they have a symbiotic relationship with. So if you have excess boron, the symptoms of a boron excess are identical to the symptoms of a calcium deficiency because it's exactly the same thing. So you can address, you can add calcium and the boron excess symptoms will disappear. The same is true of molybdenum, which causes a nitrogen deficiency. And when you address nitrogen, then the molybdenum excess problems disappear. I have only once so far observed a manganese excess where the grower applied 20 times the recommended application rate. And aside from that, I'm sure it is possible to produce excesses, but we actually observe them very, very seldom. When materials are applied at the recommended application rates, it's very unusual for us to observe excesses. Question. Might I elaborate on the traditionally recommended application rates for foliar applications of trace minerals such as 1 pound per acre of iron sulfate versus the amounts recommended for some rebound chelated products? Not sure exactly of the question that you're asking, but first they would suggest that you always follow the recommended the label rates because they are label rates for a reason. And secondly, when you calculate the quantity of actual trace mineral that you're applying on a per acre basis, usually you will be applying substantially less in terms of grams per acre of iron with an organic acid chelated material or an amino acid chelated material versus a pound of iron sulfate. It doesn't matter. What actually matters is the quantity that the plants absorb and the quantity the plants absorb in for the case. In the case of, for example, in the case of the rebound trace minerals, which I have a lot of personal experience with, will be much, much higher than when we do a foliar application of iron sulfate or manganese sulfate, even though the physical quantity applied is much greater in the case of a sulfate product. So we have to look at product efficiency and not grams of actual material applied. A question from Darren Petzer. Hi, Darren. Soil mineral analysis reveals excellent to excessive trace minerals. Leaf tissue analysis reveals the same. Can we assume that the iron and manganese in the leaf is physiologically active? Darren, in our experience, the answer is no. You cannot assume that the iron and the manganese in the leaf is physiologically active on a dry matter based tissue analysis. Particularly in the case of iron. What was observed with since we've started using SAP analysis and we've conducted this experiment many times, you can conduct a SAP analysis and a tissue analysis side by side and tissue analysis will show that you have high levels of iron. SAP analysis shows you have an iron deficiency and when you apply a small amount of chelated iron, you get this tremendous plant response, indicating the plant obviously has not had adequate iron. And interestingly enough, in some experiments that have been conducted over the last two now almost three year period, three growing seasons by one of the farmers that we work with doing continuous side by side forage analysis on forages and SAP analysis, we've observed that when we started putting on applications of rebound iron, the iron levels in the SAP analysis went up and the iron levels in the forage analysis, which is the equivalent of a dry matter tissue analysis, actually went down, that all of a sudden when the plant had adequate levels of iron in a form that it could use, it discontinued absorbing oxidized iron from the root system and moving it up into the plant where it was not physiologically active. So there was actually an inverse correlation. The better that iron was bioavailable and physiologically active, the smaller the quantities on the tissue analysis, which I found to be really interesting question from Ned o'. Brien. Are these micronutrients stored in the leaf and thus transferred to the ddery cow to help improve her health and fighting disease? Ned the answer is absolutely yes. That's foundational to developing really healthy ecosystems. Thomas Jarrett hi Thomas. For multiple years with grapes we have experienced fruit rot right as they are being ready to be picked. What may help with this? So I'm guessing that possibly may be anthracnose, although it could be a number of different organisms. Thomas the first step is to identify exactly what it is, what the organism is, and then to look up the answer in the research. The information is available online and it's available in the references that I provided. I don't know what it is off the top of my head, but it's likely to be highly probable to be some combination of the seven trace minerals that been discussing and describing. And also another approach if you don't know exactly what the cause is and this is actually an important point. See, we can do the research, we can look at, we can read the books, we can read the peer reviewed literature, we can identify what the organisms are and what the trace mineral profile is present or absent, and what is needed. Or we can take another approach. We can simply use a SAP analysis, see what is not an adequate supply, address it and watch the diseases disappear. And this has been true for us on a number of diseases that we have worked with. We've been very successful at controlling and reversing completely reversing bacterial canker on cherries for example, as well as another stone fruit. We can't point to exactly what we did that produced that result. We simply used SAP analysis and we applied whichever trace minerals were deficient and voila, bacterial canker disappeared. You can do the exact same thing. The reality is that when we look at managing plant nutrition through this lens, then we don't need to know exactly which diseases are correlated with specific trace mineral profiles. That is certainly interesting and useful and valuable information. But we can also just balance whatever the plants are low in and expect that will take care of the problem. And it does take care of the problem very effectively. Follow up question from Ned Is SAP analysis possible and useful in grass? The answer is yes, it is possible and it is useful. And I would also suggest with grasses to use an actual forage analysis as well. That can also be very useful and give us very valuable information. And then one last question. There's more questions popping through. List is getting short. How does the net charge of an applied mineral or molecule impact the plant health or susceptibility to disease? So when we look at what is happening in the plant from a biophysics perspective rather than a biochemistry perspective, we look at electron charges, reduction, oxidation, cell membrane voltage, potential, etc. Which can be measured by pH and EH and so forth. Generally we find that it is imbalances of those biophysical parameters that lead to the susceptibility of disease, and that it is these trace minerals which can help to restore that balance that will give us increased disease susceptibility. Excuse me, increased disease resistance. Question from Malcolm. We use the refractometer twice each day to measure brix levels and calcium levels and boron activity. What part of a citrus tree should I be taking the leaf from to gain the best correct results, such as the fourth leaf from the new growth from an unfruiting terminal? Is it better to target healthier plants? Malcolm, you raise a very good question. And the answer is that as you know this very well, you will get different results at different locations on the plant. I would suggest that at the very least you select two different locations, the oldest leaf and the last fully mature leaf, as you described. And remember that when we are speaking about producing disease and insect resistance and using a refractometer as an index to correlate and describe possible susceptibility, diseases and insects will show up on the weakest parts of the plant first. So when we are measuring the last fully mature leaf, the fourth leaf from the growing tip, and the brix levels show to be fine, but the brix leveled on the old leaves are not fine, then that plant is still disease susceptible and still insect susceptible. And so this is an important point that sometimes when growers use refractometers to measure disease and insect susceptibility, that we actually, in many cases, in some cases, disease and insect susceptibility shows up at a different part of the plant than what is actually being measured. So we just simply need to identify where the weakest point is and then measure the weakest point to use as our barometer and as our metric for overall disease and insect susceptibility. It's a very good question. There are a few more questions that have come through on specific diseases and specific insects and particular nutrient profiles that they might correlate with. I don't know exactly what the answers are for several of them, such as rose rosette disease. There's a question here on woolly apple aphids. Aphids, again, are related to the second stage of the Plant Health Pyramid. And I've described the minerals that are correlated with that both earlier in this discussion and also on a separate video on the Plant Health Pyramid, which is available on YouTube. So we have a lot of this information available, but again, there is, there are hundreds of diseases, hundreds of insects. It's not possible for me to answer the questions about all those here in this webinar, but the reference is available. Look it up. It's out there, and it's probably out there on our website and some of our other videos as well. So I want to thank all of you for listening and I hope that you found the information useful and enjoyable. I really enjoyed the dialogue and the participation. So thank you, all of you, for being here, and I look forward to speaking with you again in the future. Have a wonderful day. Thanks. Bye.