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Do farmers not care about their soil?

When farmers truly care about their soil, will they continue to use soil management practices that lose 2 pounds of topsoil for each pound of corn that is produced, as is currently the case in the state of Iowa?

When farmers truly care about their soil (and their neighbors), will they continue to apply excessive nitrogen fertilizer that pollutes groundwater and drinking water sources?

Many farmers do care, deeply.

Many more profess to care, but their actions testify the hollowness of their words.

We can only begin to make progress when we stop lying to ourselves.

We do ourselves and everyone else a disservice by insisting “This is the way it needs to be to grow your cheap food. We got this.”, and continuing to engage in the same behavior that got us here.

How have your management practices changed to improve soil health?

 

 

2021-07-25T19:36:08-05:00July 28th, 2021|Tags: |

How insects sense unhealthy plants

Plants constantly communicate with electromagnetic signals, and insects are tuned in to some of those signals. In the excerpt of our podcast interview, Tom Dykstra describes how insects are attracted to some plants and not to others. If you want to learn more about this fascinating topic, or have any questions,  Tom is presenting a webinar on Leaf Brix and Insect Herbivory tomorrow at 1 PM EDT. Please join us.

John: This is a fascinating piece, Tom. I know that this is something that many growers are very interested in and want to understand much better. Would you be willing and able to dig a little bit deeper into describing how the olfactory senses work and why some insects are attracted to certain regions where others are not?

Tom: Generally, the insects are smelling with their antenna and with their palps, which are some of the mouth parts. So when they’re flying through the air, they pick up various odorants in the air. And these odorants are vibrating and giving off energy. They’re absorbing and emitting energy constantly. As long as they are above zero degrees Kelvin, which is absolute zero, they are vibrating.

And these electromagnetic vibrations can be easily detected by various equipment in the laboratory, as well as the equipment on an insect. They have various sensilla. I would call them tiny antenna on the actual antenna-proper of the insect. And it’s these antenna—whether it be the antenna-proper or whether it be the smaller sensilla on the insect—that are tuned into very particular frequencies. And these particular frequencies are all important for the particular insect.

Some insects would not be tuned into CO2. They would have no reason to be. Whereas other insects, like mosquitoes, would be tuned into CO2. There are certain floral compounds given off by plants that some insects are going to be attracted to—honeybees being prominent among them. And then you have certain scents that are not attractive at all because some insects don’t go after flowers. There are some plants that advertise themselves as unhealthy. And when they do so, they are picked up by other insects.

Insects are only tuned in to the unhealthy plant. No insect will ever attack a healthy plant. What they’re zooming in on is the unhealthy plant, because it’s digestible. Healthy plants are not digestible. Unhealthy plants are. Because they can’t digest a healthy plant, there’s no interest in even attacking it. It either has to be injured or it has to be unhealthy. And then, by doing so, it is now digestible, and this is what an insect is going to attack.

At the beginning of our conversation, I mentioned how once you get above twelve Brix, insects really aren’t causing any more issues with your plants. And once you get above fourteen, they’re really not even landing on your plant, unless they just want to rest on it, because they won’t be able to take a bite. Or if they do take a bite, they won’t be able to get through the cuticle or into the phloem tissue—it’s not going to be digestible to them. They’ll have to pull out and move on to a different source.

So all insects are flying above, looking for crop plants that are digestible to them. Plants advertise themselves as being unhealthy, essentially saying, “I’m unhealthy. Please come eat me.” And so the insect will come in and it will start eating the plant, because that’s their job.

Our job is to eat healthy plants. We have a much more elaborate enzyme system. Our digestive systems are designed to eat healthy food. We don’t do well eating Doritos all the time. We do well when we eat healthy plants, and this leads us to be healthy.

For the insect, it’s different. Insects do not do well on healthy plants. They can starve. You can take a Colorado potato beetle and put it on a healthy potato plant and it will not be able to eat it. But you can take an unhealthy potato plant and the Colorado potato beetle will go to town, because this is what it is meant to do. And so because insects are only attracted to unhealthy plants, the unhealthy plants will advertise themselves. They’ve got certain visible frequencies that insects can detect, especially from a distance. And they’ve got certain odors. And these odors can be picked up by the antenna and by the sensilla, and the insect will move in for the kill, so to speak.

John: When we look at plant health, we’re talking about healthy plants versus unhealthy plants. What are some of the compounds that serve as insect attractants that we could manage and monitor?

Tom: You can’t. It would really have to be a general thing. Generally speaking, ethanol is a universal odorant that advertises itself as being unhealthy. So a lot of the plants will release not just ethanol, but also various alcohol components. Not all alcohols, but many alcohols advertise a plant as being unhealthy; it’s a hallmark of fermentation. Fermentation produces the alcohol.

And so when a plant is degrading and it’s in trouble and it’s fermenting, even in a small way—even in an imperceptible way—it will advertise itself. If these odorants are being released, they will be picked up by insects. It will change how the plants are perceived. You can take satellite images of two crop plants and they look different on various images. It can be a visible image. It can be an infrared image. But they both may be corn. They both may be soybean. They both may be anything you could think of, but they will not have the same look under an infrared camera or under a visible camera.

This is something which is very profound in grasshoppers. You don’t find them so much in the United States, but on other continents, locust swarms are a problem. These locust swarms are not just millions of individuals, but billions—sometimes trillions—of insects. They descend upon a very particular crop and take it all the way down to the roots and then pick up and fly away. And they will leave a farmer’s field right next to that exempt. These are the remarkable things that you realize when you see stuff like this— the grasshoppers made a decision. They made a decision to eat one plant over another. Why? Why didn’t they just come down and eat everything? We’ve always been told that grasshoppers will eat anything, and yet there is direct proof in some of the images that I have seen and testimonies of others that, no—they actually are very selective.

Now, I should tell you that grasshoppers are less selective than other insects. Some insects will disappear by a Brix of eight. Other insects will continue to chew on your plants right up through ten, eleven, or twelve Brix. But once they get to about twelve, they will lose interest. And the grasshoppers are among them. You can find the grasshoppers among slightly healthier plants for that reason, but you’re going to find that with the aphids, the leafhoppers, some of the other hemiptera insects, once the plant gets to eight, they lose interest in the plant. You just won’t find hemiptera insects on a plant above eight Brix. And those are the ones that have the beak that they stick into the phloem tissue and take a sip from the sugar water that is flowing around the phloem tissue.

So every insect has its own cutoff. You really have a lot of insects fall off by the time you get to eight. And as I mentioned at the beginning of this, most of the crops are between four and eight. So a lot of plants are really susceptible to every single insect that is out there. But if you can get above eight, you pretty much can take care of your aphids and your leafhoppers and psyllids. The Asian citrus psyllid is down here in Florida, and other psyllids, because it’s very rare to find a citrus tree that’s above eight. We’ve tested a lot of them.

Uniform and heavy plum tomatoes

When these indeterminate plum tomato varieties are grown in greenhouses, it is standard practice to prune back to three fruit per cluster to achieve uniform fruit size and larger fruit, with a target of six ounces per fruit.

The first year on an AEA nutrition management program, this grower observed that his plants had so much vigor and energy, he choose to skip cluster pruning, which greatly reduced labor requirements.

This resulted in a harvest of 6-7 fruit per cluster, all relatively uniform in size. The fruit uniformity and uniform ripening meant fewer hand harvest passes were required, further reducing labor costs.

The surprise was fruit weight. While the fruit was in the ideal size range, each fruit weighed an average of 8.3 ounces, instead of the 6 ounce target. As you know, this increase in fruit density correlates with improved flavor and aroma, lengthened shelf life and storability, and nutritional value.

Since the grower is paid by weight, the combination of more fruit per cluster, more weight per fruit, and reduced labor makes an immediate and dramatic difference in profitability.

2021-07-21T07:51:51-05:00July 22nd, 2021|Tags: , |

Soil and plant health in relation to dynamic sustainment of Eh and pH homeostasis: A review

We understand that organisms which are called ‘pathogens’ can be present in the soil, on the leaf surface, and even inside the plant without causing disease, without being virulent.

We know that there are a number of factors which can trigger virulence. The factors can be related to microbiome diversity, nutritional integrity or climactic stress. We can pool these factors together and term them ‘environment’.

This is the basis for the quote “Environment determines genetic expression”, in regards to potentially virulent organisms.

The question we should be asking is “What is the environment required for this specific organism to become pathogenic?”.

The question Olivier Husson has been asking is “What is the model that universally describes when plants and soil are the corect environment for organisms to become pathogenic?”

I am excited to introduce you to the MUST READ paper that answers this question. There is more valuable information contained in this paper than I can properly introduce in short post. Please read it. You will be delighted.

This paper is a longer read at 57 pages. Print it, spend some time with it. You will be glad you did.

Soil and plant health in relation to dynamic sustainment of Eh and pH homeostasis: A review

For more background information on Olivier’s extraordinary work on redox, click his name in the blog index to find his other articles, podcast episode, and his in-depth free course on Academy.Regen.Ag

2021-07-16T15:14:34-05:00July 21st, 2021|Tags: , , , , , , |

Nectar attractiveness as an indicator of plant health

In some fields pollinators will only work blossoms in the morning, until around 9 or 10 AM. In other fields of the same plant species, pollinators are collecting nectar from dawn to dusk.

In some orchards, honeybees prefer the dandelions and healing herbs (weeds) to the fruit tree blossoms. In other orchards, bees ignore the dandelions, and are visiting fruit tree blossoms all day long.

Healthy plants produce larger amounts of nectar that has a higher sugar content, which increases it’s attractiveness to pollinators.

Less healthy plants have less nectar, and the sugar content can be dramatically lower.

As an example, the sugar content of apple nectar can vary from a low of 2% up to 60%.

When apple blossom nectar contains 2% sugar, do you think honeybees will prefer the dandelions over the apples or vice versa? What about when the sugar concentration is 60% in the nectar?

An agronomist with decades of experience has reported that honeybees avoid visiting flowers where the nectar brix is below 7, since they consume more energy than they gain in return.

Before our transition to regenerative agriculture and nutrition management, honeybees would only visit cucurbit crop blossoms until 9 AM. Within two years of changing nutrition management, they were present all day.

You can observe how much time a bee spends on each flower. A flower worth visiting for 80 or 90 seconds will contain much more nectar (and of higher quality) than a flower only worth visiting for 5 seconds.

You can also observe how long during the day pollinators are active in a crop.

Both of these observations will correlate to nectar attractiveness, and to overall plant brix readings and health.

2021-07-15T10:28:51-05:00July 20th, 2021|Tags: , , , |

Sap pH as a susceptibility indicator

Bruce Tainio pioneered the use of plant sap pH as an indicator for disease and insect susceptibility in 1988. We have used this tool in our consulting work since the beginning, and have found it invaluable. Today, pH is included in lab sap analysis because of Bruce’s work.

More recently, we have learned from Olivier Husson’s work, that measuring pH by itself is incomplete, since the environmental parameters organisms require to become virulent are at least two dimensional, as they are determined by both Eh and pH, not by pH alone.

Bruce wrote this outline we shared in our newsletter in 2010, and it is still relevant today.

Plant Tissue pH = Energy
By Bruce Tainio

While laboratory soil and tissue tests are good and necessary tools, we often don’t receive the results for several days, or even up to two weeks in some cases. On a growing crop, that can be too late. With this in mind, we developed a diagnosis of plant health based on liquid pH values of plant tissue sap, which has been used in our biological program at Tainio Technology & Technique since 1989.

Simple to use and 100 percent accurate, a quick plant tissue pH test is an instant snapshot of the state of health of any plant and can tell us the following information:

  1. Enzymatic breakdown of carbohydrates (sugars) for proper growth and vitality of the plant.
  2. Risk potential for insect damage.
  3. Risk potential for foliage disease attack.
  4. Nutritional balance in the growing crop.
  5. Quality of nutrition in the fresh fruit or vegetable crop to be harvested.
  6. Shelf storage potential of fresh fruits and vegetables.


The table below is a general guideline to determine what tissue pH means. With this scale we can predict the probability of insect and disease resistance or susceptibility.



The dictionary defines pH as “a number equal to the logarithm of the reciprocal of hydrogen ion concentration within a solution.” That’s a mouthful, but more simply put, pH represents the percentage of hydrogen ions in a solution. In our case, the solution is the liquid of the plant cell, or the sap.

It is important to know that a change in the pH level of a solution of just one unit equals a tenfold change in the hydrogen ion concentration. If the pH is increased or decreased by two units, the hydrogen ion concentration changes by a hundredfold! Thus we can see why what appears to be only a slight shift in pH can spell disaster for the farmer.


A neutral pH of 7 within the cell fluid means it contains 100 percent saturation of cations other than hydrogen (in other words, the sap contains no free hydrogen ions). At a plant’s ideal cellular fluid pH of 6.4, the saturation of cations other than hydrogen is about 88 percent. At 88 percent saturation – principally of calcium, magnesium, potassium and sodium – the ionization and activity of these elements generates an electrical frequency of between 7.5 and 32 Hertz, which is one of the “healthy” frequency ranges of all living cells.

To decrease cellular pH to 6.0 is to lower the saturation of the above four principle elements to 80 percent, thus lowering the plant’s frequency to a level of lower resistance to bacterial, fungal and viral plant pathogens.

Studies have shown that insects are attracted to a tree or plant by the tree or plant’s frequency. If the saturation of Ca, Mg, K and Na increases to over 88 percent saturation, the frequency from these ions in the cell are increased, and consequently, insects are attracted to the higher-than-normal cell frequency.


The same process occurs in animal and human cells. Hydrogen accumulation in the cell tissue means the saturation of Ca, Mg, K and Na is decreasing, thus causing the frequency to decline. This low frequency leaves the cell an easy target for disease.

Oftentimes we see both insect and disease problems occurring at the same time. This can happen when insects attack due to a high plant tissue pH, and the tissue becomes weakened in the localized areas of attack. Next, localized, rapid energy loss (a drop in pH) occurs at the insect-damaged spots, resulting in tissue disease attack of those areas on the plant.

When a pH shift of a half point (0.5) or more from the ideal 6.4 occurs in the cellular liquid, a laboratory tissue test should be taken to determine exact imbalances and which materials should be applied.

Tissue pH Rule of Thumb
Low pH + Moderate Brix = Calcium Deficiency
Low pH + Low Brix = Potassium Deficiency
6.4 pH + High Brix = Balance


In the interim, for a quick adjustment to bring up the pH, calcium can be foliar applied in small amounts per acre. To quickly bring down a pH that is too high, on the other hand, small amounts of phosphate can be applied to the foliage. These types of quick fixes are usually only temporary, however, and should only be used while awaiting a complete tissue test analysis.

Like most busy people, we have neither the time nor the patience to puree the two pounds of plant tissue it takes to get enough for a conventional pH meter readings; so we use the Cardy Twin drop pH tester, made by Horiba. With this pH meter, a reading can be taken out in the field in less than one minute. We just take a few leaves, roll them up into a tight ball, and squeeze out a few drops of sap using a garlic press. Be sure and use a good quality stainless-steel press, as a cheaply made garlic press will break.

Generally, the more mature leaves on the plant will give the most accurate picture of the plant’s health, level of resistance or susceptibility to problems. Since the plant spends most of its energy supporting new growth, the pH of new leaves will not reflect the pH of the rest of the plant as a whole.

pH & SUGAR


An indirect method of determining the energy levels of a plant is to measure the carbohydrate (sugar) levels in the cell liquid. For this test, a refractometer is used to determine the level of sucrose in the cellular fluid. This reading is referred to as the brix scale.

Within a given species of plant, the crop with the higher refractive index will have a higher sugar content, a higher mineral content, a higher protein content and a greater density. This adds up to sweeter-tasting, more nutritious food with a lower nitrate and water content and better storage characteristics. Such produce will generate more alcohol from fermented sugars and be more resistant to insects, reducing the need for insecticides. Crops with higher sugar contents will also have a lower freezing point and therefore be less prone to frost damage. Soil fertility needs can also be ascertained from this reading.

The brix levels should not be taken as an exact measurement of a plant’s vitality, but rather as a guideline. Stored sugar is not a cellular energy source until its carbon-hydrogen-oxygen molecular links are enzymatically broken apart. If this line breaks or energy release occurs faster than the cell can use it, then that energy is lost into the air. This condition usually occurs when the liquid pH of the cell is below 6.4 and most often indicates low Ca and high K.

The reverse can also occur – if the links between the carbon, hydrogen and oxygen molecules of a sugar are broken too slowly due to low enzyme activity, the plant becomes starved for the energy it needs for growth. This is usually caused by low manganese or zinc, or from high nitrogen/high tissue pH levels, coupled with drought stress.

As a general rule, we can say that when a plant has a low tissue pH and a moderate brix level, there is usually a calcium deficiency involved. On the other hand, a low pH with a low brix level usually indicates a potassium deficiency. The ultimate goal is to achieve a pH of 6.4 with a high brix level.

Plant tissue pH management is a relatively small but invaluable investment of your time and budget, which cannot only help you prevent disease or insect attacks, it can stop them in their tracks even once they have gotten started. This means better yields, bigger profits and most importantly, less need for chemicals.

 

2021-07-16T13:35:05-05:00July 19th, 2021|Tags: , , , |

Mitigating heat stress

When leaf temperature becomes too warm, plants switch from photosynthesis dominant to photo-respiration dominant, and begin ‘consuming themselves’.

The threshold for C3 photosynthetic pathway plants is a leaf temperature of 78 degrees Fahrenheit (25.5 C). For C4 plants, the threshold is 86 degrees Fahrenheit (30C) leaf temperature.

Leaf temperature and air temperature are not the same. The healthier plants become, the better they are at cooling themselves. There are several mechanisms in play, topics for future blog posts. It is clear that plants with a waxy sheen on the leaf surface can have a leaf temperature as much as 8-10 degrees cooler than plants that lack nutritional integrity in the same climactic conditions.

When this threshold is crossed and photo-respiration becomes the dominant process, a few important shifts occur:

  • photosynthesis/sugar production drops or stops completely
  • plants consume the limited available sugar supply
  • plants consume any free/available lipids as an energy source (these are abundant in high energy plants, very low in plants getting nutrition from soluble ions instead of from living microbes.)
  • once the supply of available sugars and lipids has been used as, plants begin consuming their own proteins as an energy source.

80% of the nitrogen (proteins) contained in plants is in the form of enzymes. Breaking these down further weakens the plants ability to recover quickly. Protein catabolism also leads to the formation of ammonium, which is a requirement for  spider mite infections.

When plants experience periods of high heat stress, one of the best management strategies is to provide them with a surplus of energy in the form of sugars, oils, and sometimes proteins, to avoid the stress consequences of catabolism.

Foliar applications of sugars and sometimes vegetable oils can produce a tremendous crop response. In the past several weeks heat stress period, growers have reported some remarkable crop responses within 24 hours from foliar applications, both when applied proactively as a preventative, and during and after the heat stress. Rejuvenate inclusion in the foliar mix seems to consistently deliver clear visual results.

 

2021-07-16T07:01:46-05:00July 16th, 2021|Tags: , , |

Perspective on glyphosate challenges

In a recent podcast interview with John Fagan we discussed the exciting possibilities of non-targeted lab analysis, which is relatively new development, permitting a wide scan to find what compounds might be present, without know exactly what we are looking for in advance.

At the conclusion of our discussion, I asked for John’s perspective on the oft-reported challenges of glyphosate, as he was a leader in developing the more recent assays which have greatly reduced the detection limits. In our discussion, I asked for some of the citations he was referring to. You can read John’s comments and descriptions in the first two documents listed below.

I do not consider it useful to constantly focus on possible negatives like glyphosate. I much prefer to focus on solutions and developing better outcomes. On the other hand, we do need to understand some of the limitations we might be imposing on ourselves, which is why we are posting this.

There are a number of people working on alternate technologies to replace the need for herbicides in general and glyphosate in particular. I wrote a post about the use of boric acid, and several growers have reported very good success.

Description of Papers on Glyphosate

Glyphosate Safety Thresholds Table & Narrative

Paper #1-Organic diet intervention significantly reduces ur

Paper #2-Glyp Body Burden Increasing with Ag Use

Paper #3-Impact of Glyphosate on Development & Reproduction

Paper #4-Glyphosate impacts the microbiome

Paper #5-Glyphosate & GMO Corn Carcinogenicity

Paper #6-Glyphosate Causal Factor in NAFLD

 

 

2021-07-16T07:01:16-05:00July 15th, 2021|Tags: , |

Water and nutrition supply are biologically driven

As we rediscover the contributions of soil biology to plant nutrition and soil health, the phrase “biology supersedes chemistry” seems ever more appropriate.

Jon Stika succinctly describes biology as the driver of plant nutrition and soil water supply in A Soil Owner’s Manual, (which I added to my recommended reading list):

When asked if they know how to plant nutrients become available to plant roots, producer’s answers typically include the belief that fertilizer must be added to the soil, where the fertilizer dissolves in soil water and the plants take the nutrients in. In fact, 90% of the nutrients taken up by plant roots are cycled through a soil organism before becoming plant available. Virtually everything plants need is supplied by the soil organisms that live in collaboration with each living plant.1 Less than a third of the nitrogen fertilizer applied to a field ends up in the plants grown there.2 The rest is retained by some other form of life in the soil, volatizes into the atmosphere, runs off the field or leeches down below the root zone of the soil with the movement of water. Most analytical soil testing and fertilizer prescriptions are based on the response in crop production of plants grown in dysfunctional soils. The methods and prescriptions work quite well; for dysfunctional soils.3 This should come as no surprise, since most agricultural soils in the U.S. do not cycle nutrients very well, so the corresponding methods of testing and prescribing fertilizer application have evolved accordingly.

Water infiltration and nutrient cycling are just two basic examples of what we now understand are processes that are driven by the organisms living in the soil. This change in understanding of how the soil works as a biological system is a major paradigm shift for almost everyone in agriculture. Armed with this new understanding of soil function, producers can reduce and eliminate the symptoms of erosion, runoff, nutrient leaching, drought, and poor crop performance to become truly sustainable.

The bottom line is that the plant available water in the soil becomes plant available because soil microorganisms made the soil aggregates that allow the water to infiltrate and be stored in the soil. It is also soil microorganisms that cycle and make the vast majority of nutrients available to plants.

If asked, any producer will tell you that they expect their soil to grow profitable crops by supplying water and nutrients to their crops. What many folks don’t realize is that these two basic expectations of soil function (water and nutrient supply) are biologically driven. Keep the soil microorganisms happy and the system runs at peak efficiency. A more efficient system will be a more profitable system.

1. Lavelle, P. & Spain, A. Soil Ecology. (Springer Science & Business Media, 2001).
2. Stevens, W. B., Hoeft, R. G. & Mulvaney, R. L. Fate of nitrogen-15 in a long-term nitrogen rate study: II. Nitrogen uptake efficiency. Agron. J. 97, 1046–1053 (2005).
3. Laboski, C. A. M. et al. Evaluation of the Illinois soil nitrogen test in the north central region of the United States. Agron. J. 100, 1070–1076 (2008).

2021-03-02T17:49:07-05:00March 3rd, 2021|Tags: , , |

Nutrition management for disease control

We have known how to prevent and reverse plant diseases with nutrition management for a long time. The information is not new, it has just been ignored or forgotten.

Fertilizers and trace minerals can be used to increase disease severity, or to reduce or eliminate disease entirely. Many fertilization practices today are known to increase disease. This knowledge should be foundational for every farmer and agronomist, but has largely been forgotten. Perhaps because it would eliminate the need for fungicide applications?

To illustrate how rich the literature is, here in as excerpt from the opening chapter of Soilborne Plant Pathogens: Management of Diseases with Macro- and Microelements published in 1989. For an up-to-date and more modern version I highly recommend Mineral Nutrition and Plant Disease.

Written by Arthur Englehard:

A large volume of literature is available on disease control affects provided by macro- and microelement amendments. Huber and Watson in 1974 in “Nitrogen Form and Plant Disease” reviewed and discussed the effects of nitrogen and/or nitrogen form on seedling disease, root rots, cortical diseases, vascular wilts, foliar diseases and others. They summarized work from the 259 references in four tables in which they list crops, diseases and citations. McNew in the 1953 USDA Yearbook of Agriculture discussed effects of fertilizers on soilborne diseases and their control. He reviewed briefly specific diseases such as take-all of wheat, Texas root rot, Fusarium wilt of cotton, club root of crucifers and common scab of potato. Many other diseases were mentioned, as well as how macro- and microelements effect host physiology and disease. Huber and Arny in “Interactions of Potassium with Plant Disease” summarized in three tables the effect of K (positive, negative, neutral) on specific diseases. They listed 267 references in the bibliography.

The Potash and Phosphate Institute is dedicated to research and education and celebrated his 50th anniversary in 1985. It is a source of information on the use of K and P in the production of plants and the effects on plant disease. The Institute promotes a systems approach to crop production; disease control is one of the factors in the system.

Leath and Ratcliffe described plant nutrition and diseases in forage crops production. They indicated that fertilizers affect pathogens in the soil and on the host, and also can affect the pathogenicity of an organism. Presley and Bird reviewed the effect of P on the reduction of disease susceptibility of cotton.

In 1983, Graham, in Australia in “Effects of Nutrient Stress on Susceptibility of Plants to Disease with Particular Reference to the Trace Elements” discussed under the heading “Macroelements,” the effect of six essential elements on disease; and under “Micronutrients,” seven essential elements and 15 others as having been reported to influence a host-parasite relationship. He gives 305 literature citations.

Another review by Huber entitled, “The Use of Fertilizers and Organic Amendments in the Control of Plant Disease” contains a wealth of information. He indicated how the severity of 157 diseases was affected by N in table 1. In table 2, a similar listing is given for nitrate and ammonium forms of N. The effects of P, K, Ca and Mg are given in tables 3, 4, 5 and 6 respectively. Tables for S, Na, Mn, Fe, Zn, B, Cu, Si and other elements are also presented.

A literature research of the CAB ABSTRACT database utilizing the DIALOG Information Retrieval Service and using some keywords: soilborne disease, macroelements, microelements, soil fungi, Fusarium, Pythium, and Phytophthora, yielded 1500 citations published during the past 14 years.

The Future

Obviously a virtual flood of literature is available regarding the effects of macro – and micro element soil amendments on the level of soilborne disease in plants. What is lacking is the correlation of the positive factors into integrated production systems. The biggest problem now is how to organize and comprehend the mountain of available and often conflicting data. We have entered an era in which computer-aided analysis and other sophisticated tools are needed to integrate information and develop systems approaches is to growing healthy, productive plants.

One of the most rewarding approaches for the successful reduction of soilborne diseases is the proper selection and utilization of macro- and microelements. Since virtually all commercially produced crops in the developed world are fertilized, it is extremely important to select macro- and microelements that decrease disease. This is an important and viable alternative or supplement to the use of pesticides which usually only gives partial disease control.

Remember, this was published in 1989. What other things have you heard about that deserve to be generally known, but aren’t?

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