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Basic Botany

  MG Manual Reference
Ch. 1, pp. 42 - 44

The majority of the micronutrients are not mobile in the plant. Deficiency symptoms are usually found on new growth. Their availability in the soil is highly dependent upon the pH and the presence of other ions. The proper balance between the ions present is important as many micronutrients are antagonistic to each other. This is especially true of the heavy metals where an excess of one element may show up as a deficiency of another. If the pH is maintained at the proper level and a fertilizer which contains micronutrients is used once a year deficiency symptoms (with the exception of iron deficiency symptoms) are rarely found on indoor plants. Many of the micronutrients are enzyme activators.

Iron (Fe)

Absorbed as Fe++, Fe+++.
Not mobile in the plant.

Iron deficiency:

Interveinal chlorosis primarily on young tissue, which may become white and devoid of chlorophyll.
Fe deficiency may be found under the following conditions even if Fe is in the soil: soil high in Ca, poorly drained soil, soil high in Mn, high pH, high P, soil high in heavy metals (Cu,Zn), oxygen deficient soils or when nematodes attack the roots. Fe should be added in the chelate form; the type of chelate needed depends upon the soil pH.

Iron toxicity:

Rare except on flooded soils.

Boron (B)

Absorbed as BO3-
Not mobile in the plant.

Boron excess:

Blackening or death of tissue between veins.

Boron deficiency:

Failure to set seed, internal breakdown, death of apical buds.

Zinc (Zn)

Absorbed as Zn++.
Not mobile in the plant.

Zinc excess:

Appears as Fe deficiency. Interferes with Mg.

Zinc deficiency:

"Little leaf," reduction in size of leaves, short internodes, (rosetting) distorted or puckered leaf margins, interveinal chlorosis.

Copper (Cu)

Absorbed as Cu++, Cu+.
Limited mobility in the plant.
Very immobile in the soil.

Copper excess:

Can occur at low pH. Shows up as Fe deficiency.

Copper deficiency:

New growth small, misshapen, wilted. May be found in some peat soils, (potting soils).

Manganese (Mn)

Absorbed as Mn++.
Not mobile in the plant.

Manganese excess:

Reduction in growth, brown spotting on leaves.
Shows up as Fe deficiency. Found under acid soil conditions.

Manganese deficiency:

Interveinal chlorosis of leaves followed, by brown spots producing a checkered red effect.

Molybdenum (Mo)

Absorbed as MoO4-.
Immobile in the plant.
Not leachable.

Molybdenum deficiency:

Interveinal chlorosis on older or midstem leaves, twisted leaves (whiptail).

Chlorine (Cl)

Absorbed as Cl-.
Highly mobile in the plant.

Chlorine deficiency:

Wilted leaves which become bronze then chlorotic then die; club roots.

Chlorine toxicity:

Salt injury, leaf burn, may increase succulence.

Nickel (Ni)

Absorbed as Ni++.
Mobile in the phloem.
Not leachable.
Found in seeds and fruit.
Needed by plants to form urease which breaks down urea nitrogen for plant use.
Involved in the utilization of iron from the soil.

Nickel deficiency:

Decreases utilization of iron.

Nickel toxicity:

Gives rise to chlorosis and necrotic leaf margins.

Cobalt (Co)

Absorbed as Co++.
Needed by plants recently established.
Essential for nitrogen fixation.
Little is known about its deficiency or toxicity symptoms.

See also Macronutrient Outline and general information on plant nutrition.

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