| Nutrient |
Function |
Symptoms of Deficiency |
Symptoms of Excess |
| Iron (Fe) |
Required for formation of chlorophyll in plant cells. |
Yellow-green color, but veins remain green; twig dieback; reduced growth, and death in severe cases. |
Mimics phosphorus, manganese deficiency
|
| Manganese (Mn) |
Assists iron in chlorophyll formation and serves as activator for enzymes in growth process. |
Yellow-green color of young leaves, but no sharp distinction between veins and interveinal areas as with iron. |
Mimics iron deficiency; loss of foliage color, bronzing of leaf margins, necrotic areas. |
| Zinc (Zn) |
Important plant growth regulator; essential in root and plant growth. Micronutrient most often deficient in San Diego crops. |
Yellow-green color, but veins remain green; decrease in stem length; rosetting of terminal leaves; reduced fruit bud formation; twig dieback after first year |
Not known |
| Boron |
Regulates metabolism of carbohydrates in plants. Critical for new growth in plants and assists in flower pollination, fertilization, fruit set. |
Death of terminal growth; thickened, curled, wilted leaves; Reduced flowering. |
Rare except in inland deserts with high boron contaminated water. |
| Copper (Cu) |
Activator of enzymes in plants. |
Stunted growth; dieback of terminal shoots in trees; death of leaf tips. |
Reduced growth |
| Chlorine (Cl) |
Required for photosynthesis and root growth. |
Very rare; wilting followed by yellow-green color; leaf bronzing. |
Poor growth; marginal leaf necrosis. |
| Molybdenum (Mo) |
Required by plants for the utilization of nitrogen. Plants cannot transform nitrate nitrogen into amino acids without molybdenum. |
Stunting; reduced yield; lack of vigor; marginal scorching; cupping, rolling of leaves. |
Not known. |
| Nickel (Ni) |
Needed to complete the life cycle of the plant and viable seed. |
Leaf tip necrosis |
Induces iron and zinc deficiency. Interveinal yellowing of foliage. |