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Treating corn rootworm with nutrition

In Spring 2013 an organic grain crop grower in central Pennsylvania called, very concerned about corn rootworm in his organic corn crop. About 15%-18% of the seedlings  were noticeably delayed behind the other plants, and the rootworm larvae were spreading to the larger plants as well.

At this point, we had less experience managing insects with nutritional applications than we do today, and I was uncertain how much of a difference a nutritional application would make.

With the caveat that I don’t have experience with this situation, and I am unsure if the recommendation will work, I suggested a foliar application of AEA products that contained magnesium, sulfur, boron, cobalt, molybdenum, seaweed, humic substances, crab shell,  shrimp shell, and some other goodies.

The intent of the foliar was to rapidly convert all the existing free amino acids, nitrates, and ammonium which might be present in the plant sap into peptides and complete proteins. An additional goal was to trigger an immune response within the plant through the induced systemic resistance (ISR) pathway so the plant produces higher levels of phytoalexins which can disrupt the digestive system of the insects and shut them down.

The grower applied double our recommended rates. (You don’t know any farmers that have ever done that, right??)

Forty eight hours after the application, scouting showed that all the rootworm larvae were dead.

The crop went on to produce a full yield of 230+ bushels.

Since then, we have experienced similar success on many different types of insects in different crops. It is possible to not only prevent insect damage, but healthy plants will actually kill insects that persist feeding on them.

What I find particularly interesting in this example is that the insect was below ground, and could not have been directly exposed to the foliar application. This is a certain indicator that the plants nutritional profile was changed as a result of the foliar application, which produced the resistance response we were looking for.

  

2020-06-23T11:23:38-05:00June 26th, 2020|Tags: , , |

Change nutrition management for spider mite resistance

Plants have the capacity to kill insects and mites feeding on them when they are healthy enough. These potential pests don’t show up in fields at random, but only when the plant has a nutritional profile they can utilize as a food source. When you change the plants nutritional integrity with agronomy management practices, you also change the crops susceptibility to insects and pests of all types.

Spider mites are often associated with hot and dry conditions. Spider mites are not attracted to high temperatures specifically. They are attracted to plants with abundant levels of free ammonium in the plant sap.

Elevated levels of ammonium often occur in high temperature environments when plants shift from photosynthesis dominant to photorespiration dominant. When this shift to high photorespiration occurs, plants are no longer getting enough energy (sugars) from the photosynthesis process (which has slowed down or halted). To sustain themselves, they begin catabolizing proteins to use as an energy source.

The protein catabolism during photorespiration in high temperature environments usually results in the accumulation of ammonium in the leaf, which can result in the crop being susceptible to spider mites, only when the plant does not have the needed nutrients and enzyme cofactors to convert the ammonium back into proteins at night, or as soon as carbohydrate energy become available. The critical nutrients for this conversion process are magnesium, sulfur, boron, molybdenum, adequate carbohydrates in the plant, and occasionally nickel.

In these photos, you can observe the results of a nutritional correction applied through an overhead pivot on a corn crop in SW Kansas in 2015. Spider mites were present in large numbers, and the local crop scout recommended a miticide application immediately.

The pivot took 48 hours to treat the entire circle with nutrients. In the sections that had been treated 24 hours earlier the spider mites were noticeably sluggish and moving slowly. In the section that had been treated 48 hours earlier, the spider mites were completely dead. The local crop scout assumed a miticide had been applied, but this was not the case.

Healthy plants can be completely resistant to all diseases and all insects when supported with the correct nutrition and the correct microbiome.

Of course, applying more ammonium fertilizer than plants can convert to proteins in a few days is also a great attractant for spider mites, thrips, and other related pests that are thought to like ‘warm conditions’.

2020-06-23T07:17:16-05:00June 23rd, 2020|Tags: , , , |

Insects are only attracted to unhealthy plants

An excerpt from the podcast interview with Tom Dykstra:

John: What do you believe to be true about modern agriculture that other people may not believe to be true?

Tom: Insects are only attracted to unhealthy plants.

If you believe that insects are attracted to unhealthy plants, your whole thinking changes on insects. Suddenly you have no use for insecticides. It just follows with that level of thinking, because you realize, “Well, I’m not competing with insects. They’re just eating some of the garbage plants that I shouldn’t be eating. So I really don’t need to spray them anymore.”

So now all the organophosphates and synthetic pyrethroids and carbamates and neonicotinoids—they’re all unnecessary. As you reason through this, that’s one of the conclusions you come to. You have to come to it when you believe that insects are only attracted to unhealthy plants. I don’t even have to come out as an anti-pesticide guy. I can simply say that insects are not attracted to unhealthy plants. And by extension, I would say, yes—insecticides are unnecessary.

Under specific circumstances, they have their role. I will be the first to admit that I’ve had fire ants. Sometimes they come into the house. I do have a Raid can in my house. And we have had situations where the kids would leave food crumbs around. And the situation has to be taken care of. So I’m not afraid to use insecticides, and I understand that they have their place.

However, having said that, when I’m raising crops I’m never spraying it with anything.  I don’t have a knowledge of all the insecticides, but I don’t use any of them. I’m not using any herbicides or fungicides. I use insects as indicators. I go out and check my corn plants, for example, and I look to see if they’re being attacked. And if they are, I determine what insect is attacking them, and I figure out why they aren’t healthy.

For example, the first time I started planting corn, I did have a few insects that were attacking it. By the third time that I was planting corn, no insects were attacking it, but deer came in and cleaned me out. This is the difference between the insect digestive system and the mammalian digestive system: we have a higher-level digestive system. We can handle healthy food. The deer are more interested in healthy crops. They’re not going to go after unhealthy stuff. They’ll leave that up to the insects.

The degree of protein synthesis determines insect susceptibility

Plant absorption of ammonium instead of nitrate influences the degree of insect susceptibility. Excessive nitrogen in any form results in excessive soluble amino acids within the plant that enhances insect development and population growth.

From the podcast interview with Larry Phelan.

John: I’d also like to understand the insect attraction piece a bit better. You mentioned that when you have this surge of nitrogen supply on the non-organic farms from the nutrient application period, you have an increased attraction because you have a nutrient-rich food source. Why can insects not utilize plants that don’t contain high levels of amino acids as a food source? They would also contain some level of amino acids, wouldn’t they?

Larry: Yes, all plants are going to have some levels of free amino acids, and they can also digest protein—let’s keep that in mind too. But it’s going to take energy for that insect to digest that protein.

Furthermore, a lot of plants have defenses that involve the inhibition of enzymes that break down protein in the insect. These are called proteinase inhibitors. And in terms of what we call inducible defenses, this is one of the responses of many plants to insect attack. They start the production of these proteinase inhibitors in order to reduce the insect’s ability to digest that protein. It basically knocks out those proteinases in the insect. The insect doesn’t necessarily starve, but it slows its development way down.

Well, in that situation, if you’ve also given that plant these high levels of nitrogen and it’s accumulating these free amino acids, that now short-circuits that plant defense system. So, in other words, the insect doesn’t need those proteinases as much because it’s getting these free amino acids that it doesn’t have to break down.

John: Got it. That was a piece that I had always not fully understood. I’ve heard it described that insects don’t have the capacity to digest complete proteins and that they’re dependent on soluble amino acids as a food source. And that never quite made sense to me. It made sense from a theoretical perspective, but it didn’t make sense to me that plants might have no amino acids versus one plant having very high levels of amino acids.

Larry: Yeah, it’s a matter of degree. And even proteins vary in terms of their digestibility for insects too. And, of course, insects evolve enzymes that are going to be most effective in digesting the proteins they’re likely to encounter, depending on what host plant they feed on. 

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