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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+++. Iron deficiency: Interveinal chlorosis primarily on young tissue, which may become white and devoid of chlorophyll. Iron toxicity: Rare except on flooded soils. Boron (B)Absorbed as BO3- 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++. 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+. 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++. Manganese excess: Reduction in growth, brown spotting on leaves. Manganese deficiency: Interveinal chlorosis of leaves followed, by brown spots producing a checkered red effect. Molybdenum (Mo)Absorbed as MoO4-. Molybdenum deficiency: Interveinal chlorosis on older or midstem leaves, twisted leaves (whiptail). Chlorine (Cl)Absorbed as Cl-. 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++. Nickel deficiency: Decreases utilization of iron. Nickel toxicity: Gives rise to chlorosis and necrotic leaf margins. Cobalt (Co)Absorbed as Co++. |
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