How to prevent and manage aphids and other insects by managing plant nutrition

In our regenerative agriculture consulting work we have learned that it is possible to grow plants that are completely resistant to diseases and insects based on how we manage plant nutrition.

It is possible for plants to be resistant to nematodes, mites, scale, mildew, rust, grasshoppers, or any other "pest" or "pathogen" you can name. We have been able to replicate these experiences on a large scale on many different types of crops in different environments.

To describe the shifts we were observing in plant physiology and pest resistance we developed a diagram called the Plant Health Pyramid:



You can find the infographic, and a lot more information about the pyramid here.

Diseases and insects are simply natures survival of the fittest mechanisms, here to take the unhealthy plants out of the system before we can eat them.

We have found that some groups are more difficult to manage with nutrition, and some, such as aphids, whiteflies, cabbage looper, corn earworm, corn borer, armyworm, tomato hornworm, basically any larval insect, are very easy to manage with nutrition management. These insects only show up when plants contain soluble nitrates that are not being converted quickly enough to amino acids and proteins.

It can be quite easy to foliar feed nutrients and have these pests disappear in a few days. I have shared what we have learned with the large scale agricultural community, but thing this is information that deserves to be widely known to help resolve pest problems and remove any desire we might have for pesticide applications.

The nutrients which need to be supplied to resolve these insect problems are magnesium, sulfur, molybdenum, and boron. The first three are particularly critical. if the plant has enough magnesium and sulfur, but lacks adequate molybdenum, results will be limited or nonexistent.

Here is a blog post I wrote to describe the possibilities to commercial growers, you can find the original blog post here. How to Propogate Aphids

It is important to propagate aphids in our fields so the beneficial insects such as lady beetles have something to feed on. It is quite easy to produce a tremendous aphid population which can sustain a large number of beneficials and not be negatively impacted. We just need to give them the right environment.

Here are the easy steps to produce an optimal environment for aphids, which require free nitrates in the plant sap.

Step one, apply more nitrogen then the plants can utilize at the current growth stage.

Step two, do not supply magnesium for better photosynthesis.

Step three, do not apply sulfur the plants needs to produce sulfur-bearing amino acids and complete proteins.

Step four, do not supply molybdenum for the nitrate reductase enzyme.

Step five, do not apply any boron that might boost plant immunity.

If you follow these five very simple steps, you can be sure that your crop will provide the perfect food source for aphids. In addition, it will also be the optimal food source for many other larval insects such as corn rootworm, earworm, corn borer, cabbage looper, tomato hornworm, and others. Really for any larvae. Propagating these larvae provides a ready food source for songbirds and beneficial insects, a valuable ecosystem service.

Of course, if you do not desire to propagate these insects on your crops, the solution is obvious. Do the reverse of the five easy steps, and these insects will not be able to use your plants as a food source.

When we consider the implications of aphids and other "pests" being natures survival of the fittest mechanism, that means we can preferentially manage our soils and ecosystems to be optimally balanced from a microbiome and nutrition perspective for the plants we desire to thrive. The plants we desire to harvest, and those plants often referred to as "weeds" require a completely different soil nutritional balance and microbial profile.

When soils are optimally balanced for the crop, and not for the weeds, the weeds are now the unhealthiest plants in the ecosystem, and the diseases and insects begin feeding on the weeds, rather than on the crop.

Here is blog post where this occurred with aphids specifically.

Insects consume unhealthy ‘weeds’ growing in healthy soil

Not all plants grow equally well in the same soil. Each plant has a preferred microbial, physical, and nutritional environment it thrives in.

When soil balance is optimized for our domesticated plants, the crop plants are healthier than the weeds. Now, the weeds have lower brix readings, and are more susceptible to disease and insects than the surrounding crop.

These lambsquarter plants were growing at the intersection of three fields, growing tomatoes, mixed salad greens, and peas. The last two crops can be very susceptible to aphids. There were no aphids to be found anywhere on the crops, while the lambsquarter was being consumed, as you can see.



https://i2.wp.com/johnkempf.com/wp-content/uploads/2020/04/IMG_0813-1.jpg?fit=1000%2C1339&ssl=1

Another blog post describing some of the historical research on sugar metabolism and insect resistance:

Insect susceptibility determined by types of plant sugars

Sugar metabolism and carbohydrate synthesis are at the very foundation of plant health, but we generally don’t learn much about them in agronomy or even entomology. The types of sugars and the relative concentration of different sugars contained within the plant seem to be foundational in determining susceptibility/resistance to many herbivorous insects.

Here are a few excerpts from Harold Willis1 I found interesting:

The role of sugar in insect attack of plants is fascinating. Based on research done on various insect and plant species, apparently insects like moderate amounts of plant sugars and are attracted to plants containing them. But high concentrations of sugars are avoided by leafhoppers, grasshoppers, and the European corn borer2.


Alfalfa was found to be resistant to pea aphid when its stem tissues had a more acid ph and higher levels of sugar (pentoses) and pectic substances (larger carbohydrate molecules formed by linked sugars). Pentose sugars are formed from hexose sugars which are the original products of photosynthesis. Alfalfa plants that are normally susceptible to aphids will become resistant if the above-mentioned cellular changes occur3.

A possible reason that some insects avoid high sugar plants comes from research by G Fraenkel. Some sugars and sugar alcohol combinations (glucoside and mannoside) interfere with normal utilization of other sugars, and so are toxic to insects (mealworms)4. The inhibitory sugars are found mainly combined with other molecules in plants, but if digested by insects and in the presence of the sugar glucose, their toxic effects occur5.

Our knowledge of plant immunology has progressed well beyond this research in the ’40s and ’50s, but the practical application has fallen well short. I describe how we have applied these principles in our plant health pyramid infographic and on YouTube here.

1. Willis, H. Crop pests and fertilizers – is there a connection?

2. Thorsteinson, A. J. Host Selection in Phytophagous Insects. Annu. Rev. Entomol. 5, 193–218 (1960).

3. Emery, W. T. Temporary Immunity in Alfalfa Ordinarily Susceptible to Attack by the Pea Aphid. Journal of Agricultural Research 73, 33–43 (1946).

4. Fraenkel, G. Inhibitory effects of sugars on the growth of the mealworm, Tenebrio molitor L. J. Cell. Comp. Physiol. 45, 393–408 (1955).

5. Dethier, V. G. & Rhoades, M. V. Sugar preference-aversion functions for the blowfly. J. Exp. Zool. 126, 177–203 (1954).

The realization that insects and diseases can be managed with ecosystem and nutrition management means we need to think differently about "pests".

What defines a pest?

What is a pest?

When a wolf succeeds in catching a rabbit for dinner, which of them is a pest?

Is a wolf a pest while it catches rabbits and deer? When it catches a  lamb?

Is a rabbit a pest while it eats clover, or only when it eats the greens in the garden?

Is a ladybeetle a pest while it consumes aphids in the fields, or only when they swarm houses in the fall?

Is the definition of a ‘pest’ completely human-centric? It seems we call these living beings pests only when they bother us, but not when they bother other organisms we are not personally invested in.

We have deeply interdependent relationships with bacteria, fungi, viruses, nematodes, insects, amphibians, reptiles, mammals and birds of every kind. Almost all of these organisms are quite benign in healthy ecosystems. When the ecosystem is degraded, they proliferate, and begin feeding on the animals or plants we have a vested interest in. Then we proceed to label them as a pest or a pathogen.

But if it is us that has mismanaged the ecosystem, are we the pathogen?

The environment/ecosystem determines the presence and proliferation of all these living beings.

If we are to be stewards of these ecosystems, we must acknowledge that it is our management of the environment that determines whether these organisms express themselves as a benign participant or as a pest.

If we want to accept responsibility and make a difference, it does not seem useful to label living beings as pests.

Labeling is a subtle subconscious shifting of responsibility. “I am not responsible for these pests! They invaded! From out there. They are out of control. The weather was awful, the season was wet/dry/hot/cold.”

Neither the wolf nor the rabbit is a pest. They are symbionts in the environment and are dependent on the greater ecosystems they are a part of to sustain themselves.

Neither spider mites nor fusarium is a pest or a pathogen. Nor are any other insects, nematodes, bacteria or fungi. They are simply present in the environment we have created for them. If they proliferate to the point of causing crop loss, it is because we have managed the ecosystem to create an optimal environment for them.

If we desire them to not be present to the point of causing economic damage, we only need to manage the ecosystem differently.

I really would like to develop a new lexicon, we need different words rather than "weeds", "pests" and "pathogens". These words lock us into an incorrect perspective on functional ecosystems.

The german word for weeds is Heilkraüter, 'healing herbs', we need something with this definition for the english language.

Maybe insects become 'landscape healers'? What ideas do you have?

Thank you for sharing this info John. I've seen you speak at several conferences and appreciate your knowledge and approach.

I work in a commercial nursery that strives for.beyond organic propagation. The high plant density and the stress experienced by the mother plants that provide the clonal material make pest management a constant struggle. We aim for optimal plant health but do feel reliant on bio-pesticides. We currently include sea-crop as a foliar treatment as part of our ipm, is that a sufficient source of molybdenum and/or boron? Should we look at getting those minerals into our soil? Is it possible that we are just under applying the sea-crop? It is used as a foliar spray once every 7-10 days at 2 ml/gal along with a biologically derived silica and a product derived from fish, seaweed, and humates.  It is also included in our fertigation mix weekly at 2.5 ml/gal.

I suspect our soil is where we could improve the most ad its currently just a commercial, bagged, potting mix. Any suggestions on amending that sort of mix that might help?

Thank you again, applying principles I've learned from you (among others) has increased the health of the farm outside of the nursery stupendously. This years crop has received no fertigation and is shaping up to be the best quality, highest yield, and least pest damaged crop in our farms 5 year history! That's why I suspect.the nursery soil is the weak link

The presence of aphids in your crop is evidence the crop does not have enough of the four elements I mentioned, and also evidence that not enough of those elements are being supplied by the SeaCrop. I would suggest using magnesium sulfate and individual molybdenum and boron to supply the crops needs.

John Kempf wrote:I really would like to develop a new lexicon, we need different words rather than "weeds", "pests" and "pathogens". These words lock us into an incorrect perspective on functional ecosystems.

The german word for weeds is Heilkraüter, 'healing herbs', we need something with this definition for the english language.

Maybe insects become 'landscape healers'? What ideas do you have?

Space and nutrient competitors and predatory competitive  controls.  Nutrient accumulators and recyclers.

Hans Quistorff wrote:
Space and nutrient competitors and predatory competitive controls.  Nutrient accumulators and recyclers.

I don't perceive them as competitors though. Plants collaborate much more than they compete. And are insects really predators when they can't use healthy plants as a food source? We are the enablers or disablers of their predations, in any case.

I like to think of plant "weeds" as visual communication from the field. They are a way that my soil can call out to me to tell me something about its history, its present state, its needs/wants etc...

I struggle with insect pests and respecting them but as I've gotten more into breeding and seed saving I find they are wonderful tools for culling.

Maybe "signal plants" to replace weeds and "signal bugs" to replace pests. Just the shift from seeing them as enemies  or invaders to seeing them as allies offering up a message is a profound shift

I'm so glad you posted this. I didn't get my wood chips this spring and my garden paths are weed city.  Without the wood chips it's a waist of time pulling them because next week it looks like I didn't do anything. All I do is brake off the seed head when it starts to develop.  It's been very frustrating to go into my garden.  The raised beds don't have hardly any weed, but the rest is full of Johnson grass and it's covered with aphids.  I did notice the only veggie that had aphids was a zucchini that was touching the grass. I sprayed the zucchini with water and stepped on the grass so it wouldn't touch the veggies.  So far no more aphids on the veggies.  
I finally got a delivery of wood chips (requested in February) so when the weather cools down a bit I will weed and put new wood chips down, but in the mean time I wont worry about the aphid infected weeds.  Just another example of letting nature take care of the problem.  Thank you!

The link to the pyramid is broke.

Thanks for posting this. I just sent a text to let my friend know your 5 reasons his garden is aphid central, hahaha.

s. lowe wrote:I like to think of plant "weeds" as visual communication from the field. They are a way that my soil can call out to me to tell me something about its history, its present state, its needs/wants etc...

I struggle with insect pests and respecting them but as I've gotten more into breeding and seed saving I find they are wonderful tools for culling.

Maybe "signal plants" to replace weeds and "signal bugs" to replace pests. Just the shift from seeing them as enemies  or invaders to seeing them as allies offering up a message is a profound shift

Ah, I like it! We think of different plants as 'indicator species', when in fact insects, bacteria, fungi, nematodes, mites, and scale are all indicator species.

Dan Fish wrote:The link to the pyramid is broke.

https://youtu.be/g1y7MHnmoeg

This is the recent youtube video by John kempf about the plant health pyramid. I couldn't find a picture of the pyramid with pests/diseases labeled in large font. Otherwise, it will be easier to deliver the message.

Anyway, to rephrase briefly, he addressed four different levels of plant health: complete photosynthesis, complete protein synthesis, increased lipid synthesis and increased secondary metaboite synthesis.

A balanced Macro and micro nutrients(especially Mg, Mn, S, Mo and B) available to plant is critical for achieving plant health, which depends on the symbiotic relationship of plant roots and microbes in the rhizosphere.  (Reminding me of dr Redhawk's soil series)  

Each level of the health pyramid helps plants fending off different kinds of pests: which are soil borne pathogens, pests with simple digestive system, air borne pathogens and beetles/nematodes/virus respectively.

There are a lots of information and examples in the video and I highly recommend it. Thanks John!