NUTRIENT DEFICIENCY IN AFRICAN VIOLETS
Many factors relate to nutrient deficiencies. It is more than just a lack of fertilizer. Temperature affects how a nutrient is absorbed or how it functions. Light changes may deplete nutrients rapidly (e.g. bleaching). Water availability is critical to plant functions and nutrient uptake. Soil pH controls how nutrient is absorbed. Good cultural practices will maximize your violet’s use of nutrients. Poor practices may result in deficiencies.
Even in the worst cultural conditions, African violets are efficient at storing and transferring scarce nutrients to maintain life in the center of the crown. As a result, the symptoms of deficiency develop over time. Deficiencies are rarely instantly apparent.
In most cases, macronutrient deficiency is seen on the whole plant or outside leaves, while symptoms of micronutrient deficiencies will appear in the center, newest leaves.
SYMPTOMS RELATED TO A DEFICIENCY OF SPECIFIC NUTRIENTS
Effect generalized OR localized on older leaves
Effect generalized and includes yellowing or drying up of older leaves. Acute stages develop red/purple color in lower leaves.
- NITROGEN
- Color fades, beginning with tips and margins of leaflets, until all foliage becomes a lighter green than normal. In time, color may fade to pale yellow. In extreme cases, margins of lower leaves become devoid of chlorophyll and curl, sometimes ‘firing.’ Stunted overall growth and loss of leaves are characteristic.
- PHOSPHORUS
- Foliage crinkly and dark green. In acute cases older leaves become purplish. Plants are stiffly erect. Petioles, leaflets, and leaf margins take an upward direction. Leaflets are often cup-shaped (spooned). Leaves fail to grow to normal size. Cell division slows causing lack of roots/flowers.
Effect localized on older leaves, occurring as mottling or chlorosis, with or without necrotic spots, but with little drying of older leaves.
- MAGNESIUM
- Older leaves lighter green than normal. Chlorosis begins at tips and margins of lowermost leaves and progresses between veins toward center of leaflet. Eventually, tissue between veins is filled with brown dead areas. Definite bulging between veins and thickening of foliage occurs. Affected leaves are brittle.
- POTASSIUM
- Foliage is more darker green than normal. Leaf is reduced in size. Internodes remain short. Plants have a humped-up, re-curved appearance. Foliage becomes crinkled, and veins appear sunken. Later, the older leaves become slightly yellow, then bronzing develops from tips and margins and gradually involves the entire plant.
- ZINC
- Older leaves are chlorotic and develop grayish-brown to bronze, irregular spots, first usually on leaves midway of plant, eventually affecting all the foliage. Spots become sunken, and involved tissue finally dies. In extreme cases, internodes remain short and leaves small and thick. Spots develop on petioles and stem; top leaves assume a slightly vertical position, and margins of leaves may curl upward.
- Older leaves are chlorotic and develop grayish-brown to bronze, irregular spots, first usually on leaves midway of plant, eventually affecting all the foliage. Spots become sunken, and involved tissue finally dies. In extreme cases, internodes remain short and leaves small and thick. Spots develop on petioles and stem; top leaves assume a slightly vertical position, and margins of leaves may curl upward.
Effect localized on newer leaves of the plant
Terminal bud (center growth) dies preceded by unusual distortions at the tips or bases of the young leaves making up the terminal bud.
- BORON
- The young leaves of the terminal bud are lighter green than normal, the lighter color being most pronounced at the base. Stem tips may die or be distorted. Internodes remain shortened, giving the plant a bushy appearance. Leaves become thickened and roll upward, and leaf stalks become brittle. Anthocyanin (purple pigment) may develop. Tips and margins, especially of older leaflets, die prematurely.
- CALCIUM
- Earliest symptom is a light-green band along margins of young leaflet of terminal bud. Such areas often die, giving the leaflet a crinkled or buckled appearance. In some cases, young leaves at top remain folded, causing tip to die. Margins of leaflets often roll upward. Auxillary buds (suckers) may show same symptoms as terminal bud.
Terminal bud (center growth) remains alive, chlorosis of newer leaves with or without spots of dead tissue, veins light or dark green.
- COPPER
- The young leaves of the terminal bud are lighter green than normal, the lighter color being most pronounced at the base. Stem tip may die or be distorted. Internodes remain shortened, giving the plant a bushy appearance. Leaves become thickened and roll upward, and leaf stalks become brittle. Anthocyanin (purple pigment) may develop. Tips and margins, especially of older leaflets, die prematurely.
- IRON
- A slight uniform chlorosis first develops in the young leaves. Tips and margins maintain green color the longest. Principal veins retain normal green color. Affected tissue gradually becomes pale yellow. Foliage becomes white in extreme cases. No dead spots in evidence.
- MANGANESE
- Areas lighter green than normal first developed between veins of leaves and in tops of stems. These areas may become yellow to white. Numerous small brown patches develop which in time become more extensive. Lower leaves least affected. Mild shortage causes only slight chlorosis, chiefly confined to upper parts of the stem, and no dead spots develop.
- SULFUR
- Symptoms develop slowly. A general yellowing of the leaves and veins occurs similar to that in nitrogen deficiency without leaves drying up. Growth of the plant is materially checked. Some spotting of the leaves occurs if shortage is acute or prolonged.
Author unknown. Handout shared at an AVSA Convention in program presented by Dr. Charles Cole.
