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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?

Insect and disease attraction to plants with reducing sugars

How is it possible for a high Brix plant to be resistant to insects and not provide them with an abundant food source when insects are attracted to sugars? The key insight is that plants contain different concentrations of different carbohydrates at various levels of plant health. The goal for optimal plant health is to have all photosynthates and soluble sugars such as glucose and fructose converted to non-reducing sugars in each 24-hour photoperiod. This means a healthy plant will have a high Brix concentration and very low levels of reducing sugars.

From the podcast interview with Don Huber.

John: Are there any negative health consequences of plants having high levels of fructose and glucose?

Don: Yes and no, depending on what other stresses there are present. If you have a deficiency of manganese, for instance, it can’t store the reducing sugars―glucose and fructose―that are being produced through photosynthesis. It can’t store them as sucrose, and so they become very attractive reducing sugars, and they become very attractive to insect pests and to a number of plant pathogens.

Manganese is a critical factor for that sucrose-phosphate synthase enzyme that converts glucose and fructose into sucrose for storage. If you’re deficient in manganese, you’ll have high reducing sugars―glucose and fructose. As insects like aphids fly over these plants, they can detect that high reducing sugar, and for them, it’s a red flag saying, “Hey, come in for dinner!” But if those sugars are converted to sucrose and stored there, you don’t see that attraction.

Reducing sugars come out of the root system―they’re the root exudates that are attracting Pythium and Phytophthora and Aphanomyces and those other oomycete pathogens―root-rotting pathogens.


John: Don, you described how the carbohydrate profile can attract aphids. Are there other insects that can be attracted by the carbohydrate profile?

Don: A lot of them are. I don’t know that all of them are, but many recognize the difference between the reducing sugars, and they don’t seem to be attracted to the non-reducing sugars nearly as much. You’ll see that association. When we get the minerals balanced for the plant, you’ll see all of those problems start to disappear or be very minor.

P.S. I appeared as a guest on The Modern Acre podcast in this episode.

Fungal mycelium and shutting down phytophthora in peppers

A bell pepper field had phytophthora problems severe enough to cost the entire crop.

Ridomil Gold treatments were known to be completely ineffective.

Instead of anti-biotics, we applied pro-biotics, microbial inoculants of mycorrhizal fungi, a range of bacterial species, and biostimulants through the drip irrigation system.

Within weeks the soil is filled with these thick strands of mycelium/plant roots and the crop recovered completely.

The phytophthora symptoms disappeared.

What have you seen something similar to this in the soil? What do you think this might be?

2020-09-04T14:33:10-05:00September 7th, 2020|Tags: , , |
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