Nitrogen is the element most likely to be deficient. Nitrogen is part of all amino acids which make up all of the proteins, and the protoplast. It is required in enzymes and the chlorophyll molecule.
Nitrogen deficiency symptoms begin as pale green leaves, often smaller than normal; and stunted, weak shoot growth.
Most soils in California contain plenty of Phosphorus so you are unlikely to see Phosphorus deficiencies in field or landscape situations.
Phosphorus is a structural component of nucleic acids which are basic building blocks of DNA and RNA. Phosphorous is necessary for cell division and the regulation of all cell processes.
Phosphorus deficiency symptoms begin with reduced growth with short, thin shoots. Leaves are small, and defoliation follows starting with the lower leaves.
Sufficient amounts of Potassium are present in most California soils so Potassium deficiencies are not commonly seen in field or landscape situations.
Potassium deficiencies are first characterized by reduced growth, weak stems, and shoot die-back. Early symptoms may be difficult to distinguish. Leaf symptoms include dull bluish-green discolorations, particularly in the interveinal areas of the leaves, dull, general chlorosis particularly at the leaf tips and margins; then tip burning and marginal scorch on the older leaves with the leaves curling under or upwards
Sulfur is a component of some amino acids so it is vital to protein structure. It is also in some plant hormones, is associated with chlorophyll synthesis, it aids in the synthesis of oils and is essential to the development of root nodules necessary for nitrogen fixation.
Deficiencies are common to South Eastern USA, the Pacific Northwest, Western Australia and in California, and are more common than in previous years as there is less Sulfur Dioxide in the atmosphere, and we have moved to high analysis fertilizers which are less likely to contain sulfur in their chemistry.
Symptoms of Sulfur deficiency are much like those caused by Nitrogen: reduced leaf size, stunted growth, chlorosis, orange to purplish pigmentation and delayed maturity.
Much of the Calcium in a plant exists as a structural element in primary cell walls, and as a regulator controlling new growth. It also affects structure and permeability of membranes, and helps to regulate hydration of the protoplast.
Calcium deficiency symptoms appear initially on the young leaves and the shoot apex. New leaves are distorted with hooked tips and curled margins, which are irregular and may show brown scorching or spotting. Calcium deficiency can also cause roots of the plants to become stunted, translucent, and bulbous with dead tips.
Magnesium is present in the chlorophyll molecule and is responsible for the initial absorption of light energy.
Magnesium deficiency is common in the South East USA because the parent material producing the soils contains Calcium to the almost complete exclusion of Magnesium.
Magnesium deficiency symptoms begin with chlorosis, sometimes with red or orange coloration on the oldest leaves. As symptoms progress the older leaves shrivel and drop, the veins on the remaining leaves stay green and the interveinal areas have an orange chlorotic mottle. Growth can be much reduced.
Iron is contained in chemicals that catalyze a number of reactions in plants. It is a catalyst for the production of chlorophyll, it is involved in the formation of chloroplast protein in leaves and is part of the protein that acts as an oxygen carrier and transporter of electrons.
Iron deficiency is the second most common deficiency in California. It is particularly common on plants considered acid loving in our alkaline soils.
A deficiency of Iron causes a decrease in the size of chloroplasts, reduced chlorophyll and reduced photosynthesis. Symptoms include yellow or white chlorosis between green veins on younger leaves and poor vigor leading to death of the shoot tips. These symptoms are most serious in poorly drained, alkaline soils.
Manganese is associated with oxidation-reduction reactions in plants, and in the synthesis of chlorophyll. It is a constituent of enzymes involved in respiration and is essential for photosynthesis.
Symptoms of Manganese deficiency start as interveinal mottled chlorosis, the leaves become yellow and then develop small necrotic lesions in the most chlorotic areas. Reduced leave size and crimping of leaf margins are also possible symptoms.
Zinc is involved in auxin formation in the plant and is a component of some enzymes involved in metabolism. Zinc indirectly regulates stem elongation and cell enlargement and is important to normal flower development.
Zinc deficiency symptoms begin with interveinal chlorosis. The first leaves in the spring on trees remain small, the stems fail to elongate and the leaves appear to be in whorls or rosettes.
Plants require only a small amount of Boron and requirements and sensitivity vary greatly from plant to plant. Boron affects flowering and fruiting, pollen germination, cell division, metabolism, photosynthesis and other functions in the plant.
Boron deficiency symptoms vary between plants but some general symptoms are injury to plants meristem and actively dividing tissues and death of the apical meristem. This can lead to a bushy plant habit or the death of all buds preventing new growth.
Copper is essential as a component of certain plant enzymes, is involved in photosynthesis and in chlorophyll synthesis.
Copper deficiency occurs in sandy soils of the Southwest. Symptoms are variable but generally consist of a lack of vigor, smaller than normal leaves, and a bluish-green cast to the leaves.
Molybdenum is associates with nitrogen metabolism in plants and is associated with nitrogen fixation by Azobacter bacteria. Plants require minute amounts on Molybdenum yet definite diseases are caused by its absence.
Symptoms of Molybdenum deficiency start with the older leaves and progress towards the tip. The first symptom is yellow-green or pale orange interveinal mottling distributed uniformly over the leaf. Marginal wilting, inrolling and cupping follow the chlorosis and flower formation is suppressed.