Guide to Micronutrients

Biologists have identified about two dozen minerals that are deemed essential to plant life. Among these, Carbon, Hydrogen, and Oxygen are supplied by air and water. Most fertilizers provide what are termed primary minerals: Nitrogen, Phosphorus, and Potassium – the N-P-K listed on the package. The remaining minerals are generally termed micronutrients, although plant scientists will distinguish between the secondary minerals Calcium, Magnesium, and Sulfur from a list of a dozen or more specific micro-nutrients.

CHARACTERISTIC SYMPTOMS OF NUTRIENT DEFICIENCIES

Leaves	Tip growth is small or ceases	Zinc deficiency
	Thin and brittle	Magnesium deficiency
	Mottled, blotches, or dead areas	Zinc deficiency
	Curl upward and elongation slow or ceases	Iron or magnesium deficiency or insects
	Curl downward	Boron deficiency or insects
	Collapsed spots on young leaves	Zinc or magnesium deficiency
	Tips dead	Phosphorous deficiency, excess chlorine
	Tips appear burnt	Nitrogen deficiency or fireblight virus
	Color loss at tips, striping between veins	Magnesium deficiency
	Tips and margins dead	Burn from wind, frost, salts or little water
	Scorched effect on margin	Potassium deficiency
	Yellowing margin with streaks or striping	Phosphorus deficiency or excess boron
	Margins of lower leaves browning	Potassium deficiency
	Scalloped appearance	Calcium deficiency
	Yellowing veins, pale green between veins	Nitrogen deficiency
	Green young leaves with yellow veins	Iron deficiency
	Green veins but loss of color in between	Over watering plus maladies that follow
	Grayish-brown to bronze colored spotting	Magnesium deficiency
	Green/yellow & white patterns cover leaf	Virus
	Abnormal dark green	Calcium deficiency
	Purplish color	Phosphorous deficiency
	Purplish red color	Magnesium deficiency
	Blanched color	Copper deficiency
	Yellow streaks on mid-ribs and edges	Virus
	Yellow-green overall	Nitrogen deficiency, often over-watering
Stems	Hard and brittle	Sulfur deficiency
Stems	Weak	Calcium or potassium deficiency
Buds	Dried out and dying or absent	Calcium deficiency
	Premature drop but stems are healthy	Zinc or calcium deficiency
	Reduced formation, esp. dead exterior	Zinc deficiency
	Light green color	Boron deficiency
Twigs	Dying back or brown spots	Zinc or copper deficiency
Twigs	Brown spots on leaf-stalks, weak twigs	Magnesium deficiency
Fruit	Poor or zero development	Phosphorus or iron deficiency
	Delayed maturity	Phosphorus deficiency
	Shriveled	Potassium deficiency
	Sour	Copper deficiency

BE CAREFUL WITH SOURCES OF SECONDARY MINERALS AND MICRO-NUTRIENTS

Applying a single micronutrient to a plant is a poor idea unless a chemical test of the plant or soil has determined both the type and amount of deficiency. Too much or too little of one micronutrient can have a dramatic effect on a plant’s ability to uptake other nutrients. Raw sources of micronutrients such as unprocessed seaweed extract have unbalanced, variable loads of minerals and can actually hurt your plants more than help them. Choose a product that has been refined for plants, or a general-purpose liquid chelation of micronutrients for plants. An agricultural formula that is rich in one mineral (e.g., Cobalt) should only be applied if the crop and chemical testing warrant it.

UNBALANCED MICRONUTRIENTS CAN BE A REAL PROBLEM

Excess Aluminum depresses Magnesium, Calcium, Zinc, and Manganese

Excess Cadmium depresses Copper

Excess Calcium depresses Manganese, Magnesium, and Phosphorus

Excess Cobalt depresses Iron

Excess Copper depresses Iron, Zinc, and Phosphorus

Excess Iron depresses Potassium, Phosphorus, and Copper

Excess Magnesium depresses Phosphorus and Calcium

Excess Manganese depresses Iron, Phosphorus, Potassium, and Magnesium

Excess Phosphorus depresses Zinc, Iron, Calcium, and Magnesium

Excess Potassium depresses Sodium, Iron, and Manganese

Excess Sodium depresses Potassium

Excess Zinc depresses Iron, Copper, Phosphorus, and Cadmium