Healthy Plants Are Resistant to Disease and Infestation

The tremendous task of producing adequate food for the people of our country has emphasized the problems of plant diseases and infestation.

The current methods of control emphasize the wide use of poisonous chemicals in ever increasing dosages and toxicities. This has led to the need for many persons in the fields of medicine, public health, and related sciences to study both the immediate and long-term effects on humans of such pesticides.

How to grow disease and pest-resistant crops has received small attention from most agriculturists, beyond the importation of hardier plant varieties. There have been a few outstanding men in the world, however, who have experimented in raising hardier and at the same time, more nutritive plants. Among these are: Sir Albert Howard of England, Dr. Ehrenfried Pfeiffer of the Netherlands and U.S., and Dr. William Albrecht of the U.S.

Dr. William Albrecht has shown that deficiencies or imbalances of a plant’s major nutrients alters its uptake of vital trace elements and produces a corresponding alteration in the health of the plant, causing it to be susceptible to disease and infestation. Thus, knowing the cause, suggests the cure, with two valuable benefits to humans. First, there will be a greatly decreased need for the heavy use of pesticides; and second, such healthier plants will produce a higher level of health in the animals and humans who eat them.

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If the problem of plant nutrition is one of soil fertility elements as delicately balanced as is the nutrition of humans and animals, then the matter of deficiencies in trace elements for plants might be considered the result of imbalances, often in the major elements research on these tells us that both imbalances and deficiencies of the major elements may bring failure in the plant’s equipping itself to take trace elements from the soil to the same degree as when those are properly balanced.

If we grant the truth of the plausible theory that copper is needed by plants to grow their antibiotics to protect them from fungus attack,¹ then a demonstration of balanced fertility (calcium in relation to potassium) growing potatoes free from scab, while its imbalance did not,⁴ suggest that the balanced fertility may have produced compounds in the root hair which moved the trace element, copper, into the potato for its protection against the scab fungus. 

It has been demonstrated² that inoculation as a means of helping soybeans produce more protein (in contrast to non-inoculation and bacterial absence with less protein in the plants) increased the extent to which the constant stock of exchangeable major cations moved from the refined clay into the plants. Since copper is a cation, we may well postulate that the higher concentration of protein in the potato plants by better balance of fertility was moving more copper into those plants too. Thereby they might be scab-free under balanced fertility but not under the imbalance of it by that difference in copper intake because of imbalance of the major elements. According to such thinking, then, the trace elements may actually be present in the soil when imbalanced plant nutrition in respect to major nutrient elements keeps them out of the plant and leads us to believe the soil deficient in trace elements. By applying the latter, their higher concentrations may or may not move enough of them into the plant to exhibit their effects–either direct or indirect–in protecting it. 

If the varied interrelation of calcium to potassium in growing potatoes either protects from, or invites, the fungus scab to suggest the plant’s taking, or failing to take, possibly copper from the soil for antibiotic service in the potato plant, in like manner the interrelation of nitrogen and calcium also suggested variable plant protection against insects in the growth of spinach (Figure 1). Whether trace elements were involved was not tested. But with the effects by calcium of mobilizing other elements from the soil already granted³ and with the effects also by proteins for the synthesis of which nitrogen helps, there may have been more of some trade elements moved into this crop to create the specific protective proteins rather than only more crude proteins in general.

 

Figure 1–Spinach with 10 mg. equiv. and less of nitrogen offered in the soil was attacked by the thrips insects. However, as the amount of calcium was increased, there was more self-protection against thrips grown into the plants and less insect attack resulted.

 

Plants with 20 mg. equiv. and more in the same experiment were “immune” from insects.

 

In another illustration, with the interrelation of the two major elements, nitrogen and phosphorus in better balance in the soil growing com, was the protection of the grain against damage by the lesser grain borer. Grown on a highly fertile soil of South Dakota treated with applications of nitrogen only, the sample ear of corn grain under observation in storage was badly damaged while the sample ear grown on the same soil fertilized with both nitrogen and phosphorus and stored in contact with the infested ear was not.

References Cited:

1. Albrecht, Wm. A.: “Trace Elements and Agricultural Production.” Jour. of Appl. Nutrition, VIII: 352-354, 1955.
2. Hampton, Herbert E. and Wm. A. Albrecht: “Nitrogen Fixation, Composition and Growth of Soy Beans in Relation to Variable Amounts of Potassium and Calcium.” Mo. Agr. Expt. Sta. Res. Bull. 381, 1944.
3. Klemme, A. W. and Wm. A. Albrecht: “Limestone Mobilizes Phosphates into Korean Lespedeza.” Jour. Amer. Soc. Agron., 31: 284-286, 1939.
4. Schroeder, R. A. and Wm. A. Albrecht: “Plant Nutrition and the Hydrogen Ion. II Potato Scab.” Soil Science, 53: 481-488, 1942.