Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

metallic elements. Man-made chelates are designed for use in different situations. DTPA is most effective in a pH below 6.5, EDDHA is effective up to a pH of 8, and EDTA chelate is slow to cause leaf burn.
    Chelates decompose rapidly in low levels of ultraviolet (UV) light including light produced by HID bulbs and sunlight. Keep chelates out of the light to protect them from rapid decomposition.
    Chelate - combining nutrients in an atomic ring that is easy for plants to absorb.
    This information was condensed from Canna Products, www.canna.com .
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    Technical Information: Zinc works with manganese and magnesium to promote the same enzyme functions. Zinc cooperates with other elements to help form chlorophyll as well asprevent its demise. It is an essential catalyst for most plants’ enzymes and auxins, and it is crucial for stem growth. Zinc plays a vital part in sugar and protein production. It is fairly common to find zinc-deficient cannabis. Deficiencies are most common in soils with a pH of 7 or more.
    Deficiency: Zinc is the most common micro-nutrient found deficient. First, younger leaves exhibit interveinal chlorosis, and new leaves and growing tips develop small, thin blades that contort and wrinkle. The leaf tips, and later the margins, discolor and burn. Burned spots on the leaves could grow progressively larger. These symptoms are often confused with a lack of manganese or iron, but when zinc deficiency is severe, new leaf blades contort and dry out. Flower buds also contort into odd shapes, turn crispy dry, and are often hard. A lack of zinc stunts all new growth including buds.
    Progression of deficiency symptoms at a glance:
    Interveinal chlorosis of young leaves.
    New leaves develop thin, wispy leaves.
    Leaf tips discolor, turn dark, and die back.
    New growth contorts horizontally.
    New bud and leaf growth stops.
    Treat zinc-deficient plants by flushing the growing medium with a diluted mix of a complete fertilizer containing chelated trace elements, including zinc, iron, and manganese. Or add a quality-brand hydroponic micronutrient mix containing chelated trace elements.

Early stage of Zn deficiency.

Progression of Zn deficiency.

Later stage of Zn deficiency.
    Toxicity: Zinc is extremely toxic in excess. Severely toxic plants die quickly. Excess zinc interferes with the iron’s ability to function properly and causes an iron deficiency.
Manganese (Mn) - immobile
    Practical Information: Manganese deficiency is relatively common indoors.
    Technical Information: Manganese is engaged in the oxidation-reduction process associated with the photosynthetic electron transport. This element activates many enzymes and plays a fundamental part in the chloroplast membrane system. Manganese assists nitrogen utilization along with iron in chlorophyll production.
    Deficiency: Young leaves show symptoms first. They become yellow between veins (interveinal chlorosis), and the veins remain green. Symptoms spread from younger to older leaves as the deficiency progresses. Necrotic (dead) spots develop on severely affected leaves which become pale and fall off; overall plant growth is stunted, and maturation may be prolonged. Severe deficiency looks like a severe lack of magnesium.
    Treat deficiency: Lower the pH, leach the soil, and add a complete, chelated micronutrient formula.
    Progression of deficiency symptoms at a glance:
    Interveinal chlorosis of young leaves forms.
    Interveinal chlorosis of progressively older leaves forms.
    Dead spots develop on acutely affected leaves.
    Toxicity: Young and newer growth develop chlorotic, dark orange to dark, rusty-brown mottling on the leaves. Tissue damage shows on young leaves before progressing to the older leaves. Growth is slower, and overall vigor is lost. Toxicity is compounded by low humidity. The additional transpiration causes more manganese to be drawn into the foliage. A low pH can cause toxic intake of manganese. An excess of manganese causes a deficiency of iron and zinc.
Iron (Fe) - immobile
    Practical Information: Iron is available in a soluble chelated form that is immediately available for absorption by the roots. Deficiency indoors is common in alkaline soils.
    Technical Information: Iron is fundamental to the enzyme systems and to transport electrons during photosynthesis, respiration, and chlorophyll production. Iron permits plants to use the energy provided by sugar. A catalyst for chlorophyll production, iron is necessary for nitrate and