Healthy, deep green leaves signify that chlorophyll is hard at work in a plant building food.
When the green fades to anemic yellow, the plant fails to trap sufficient sunlight and gradually peters away.
New, young foliage is likely to show more symptoms than the old leaves.
This loss of green, called chlorosis, seems to be increasing in frequency everywhere, but it is especially a problem in the arid West. Perhaps 50% percent of the home plantings suffer from some degree of chlorosis.
Even in climates as relatively moist as Florida, the Great Lakes region and Minnesota, chlorosis is common.
Research has pinpointed the chief causes of chlorosis. The anemia occurs mainly because minor or trace elements, needed only in minute quantities, are nonetheless not available to the plant.
Some trace elements never appear in finished plant tissue but are indispensable catalysts triggering the formation of the plant’s vital green element chlorophyll.
Soils Lose A Delicate Balance
Native vegetation and virgin soils were pretty well adjusted before man started upsetting things.
Primeval plants would not have survived where they were susceptible to trace deficiencies.
But man searches out strange crops in the far corners of the world and plants them on soils cleared of vegetation that nature put there.
He grows crops the soil over and over, hauling away minerals in the crop. He burns up the organic content by intensive cultivation, substitutes for it a concoction of major minerals that spur plant growth aka fertilizer.
He cultivates, he limes, he sprays and he sets fires. No wonder soils become unbalanced under these pressures for beautification and for feeding a burgeoning civilization.
Chelates A Practical Help
Soils in your yard are likely to be even more disturbed than those of the fields.
They may be exhausted to start with, and then what topsoil there is becomes buried under the subsoil from the foundation digging.
Plaster, cement leftovers, paint thinners and what not are cast upon the ground. It is a tribute to soil’s great buffering ability that anemia is not even more commonplace in the garden than it is.
It’s hard to know whether the increase in chlorosis is really the result of profound soil alteration the longer the earth is cropped, or whether scientists are simply getting better at recognizing deficiency problems.
In any event, trace deficiencies are receiving more and more scientific attention.
Fortunately, practical help is at hand through the use of chelates (pronounced KEY lates).
What Are Chelates?
Chelates are organic carriers that deliver the missing trace mineral to the plant without having it roadblocked in the soil.
The list of plants that may show trace deficiencies is long.
Some Plants That Might Be Anemic
Iron deficiency chlorosis is often found among these plants listed below, especially in alkaline soils. They usually respond to treatment with an iron chelate.
- Aster Plants
- Bleeding Heart
- Calla Lilies
- Four o’clock
- Tomato Plants
Another sensitive species is the pin oak, which seems physiologically unable to extract the necessary iron from the soil under alkaline conditions even though neighboring trees of another breed have no trouble.
But many species tolerant of lime – strawberries, roses, gladiolus, even soybeans – suffer in some areas.
On alkaline spots, even the vaunted Kentucky bluegrass may exhibit temporary chlorosis during the cold wet weather of early April.
Warmer weather and drier soils cure the trouble. But as with most plants, iron chelate speeds recovery. Chlorotic holly (Ilex crenata) drenched with iron chelate shows almost immediate recovery.
Learn More about the use of Iron Chelate
Lawns May Be Chlorotic
Proven lawn grasses such as Kentucky bluegrass, fine fescues, and bentgrass are seldom anemic if amply fertilized. But lawns may risk chlorosis on alkaline soils from western Kansas to Arizona and eastern Oregon.
In some cases, they may need periodic applications of iron.
Iron chelate, about a pound for each 1,000 square feet of lawn, provides a long-lasting preventive of chlorosis.
Other grasses, may show iron chlorosis if the soil reaction gets somewhat out of balance.
Even ubiquitous bermudagrass is known to suffer chlorosis occasionally. Centipede lawns in the South frequently turn chlorotic if the normally acid soil becomes even slightly alkaline.
Centipede is very sensitive and seems unable to extract iron from the soil in required amounts unless the pH is just right.
Anemia is not always due to iron deficiency.
Zinc, copper, manganese, molybdenum and other trace elements may be lacking in some areas.
“Unavailable” iron, however, is the most common cause of chlorosis, easily induced by alkalinity.
If your garden shows unaccountable yellowing of foliage, try an iron chelate.
If it is an iron deficiency the veins of the leaf usually remain green while the tissue between veins blanches, a telltale symptom.
Unavailable Though Abundant
Whenever a soil gets much out of balance – too acid as well as too alkaline – some vital elements tend to become “tied up.”
They are not available even though possibly abundant in the soil in an insoluble form.
Liming acid soils, or acidifying alkaline ones with sulfur and gypsum, may in time eliminate chlorosis.
Meanwhile, iron applications bring color back and may save the planting. An iron chelate such as (Sequestrene 138 Fe iron chelate – a commercial form) helps make certain that the deficient mineral will not be fixed by the soil, but instead will remain reasonably available to the plant.
The Part Iron Plays
Most of us amateur soil scientists will admit that we know little about how chelates actually operate, and how trace elements function in the soil and in the plant.
The soil and the internal mechanisms of the plant are exceedingly complex, affected by many subtle influences.
Evidently, though, the formation of chlorophyll requires iron, even though iron is not part of the chlorophyll molecule.
Apparently, too, the trace elements must be absorbable by the plant.
Chelates are science’s answer for making them more surely and continuously available to a plant, even if all the complicated antagonisms and interrelationships within the soil are not clear.
Chelates are used in such small quantities that they are not really expensive. A few cents worth, say one percent added in a fertilizer, makes sure that trace elements will be present and available.
Where chlorosis is an expected hazard, it would seem advisable to mix iron chelate into the soil as a matter of routine before making plantings.
Where growing plants are chlorotic, chelates may be stirred into the top inch of soil, or be flushed down to the roots with water poured into a dished-out surface about the plants.
For trees, holes may be punched into the soil and filled with a mix of sand, soil or fertilizer and chelate.
Not a great deal of chelate is needed, just a few ounces sufficing to save a tree.
An Economical Treatment
It is certainly less costly to treat a chlorotic plant than to replace it.
Fifty gardenias dying of chlorosis in a garden would cost hundreds of dollars to replace.
However, they could be saved with an annual application of just a few dollars worth of chelated iron.
Roses and other woody plants survive winter better after chlorosis has been corrected with chelates, compared to plants permitted to enter winter in an unhealthy condition.
So don’t despair where anemia threatens. Iron or other trace elements can be made “available” by:
- Keeping the soil aerated and on the dry side
- Bringing the pH to a level of mild acidity
- Insuring the gradual release of the deficient mineral by supplying it in the form of a chelate.
Spring treatments just before leaf buds expand is probably the most effective time to apply chelates.