Chlorosis is the yellowing of plant tissue due to limitations on chlorophyll synthesis, and can be caused by many things. This yellowing can be generalized over the entire plant, localized over entire leaves or isolated between some leaf veins. Nutrient deficiencies may not be as apparent and with striking symptoms such as chlorosis on the plant, especially when a mild deficiency is occurring. However, significant reductions in crop yields can occur with such deficiencies, especially if it leads to blossom end rot and/or blossom drop. But some deficiencies and toxicities can only be detected with plant tissue analysis, however, experience with growing a specific plant species or variety can greatly help in distinguishing poor crop performance and possible nutrient deficiency symptoms from normal plant growth.
Essential Tomato plant nutrient deficiencies and toxicities
Boron deficiency, Blackened areas at tip of stem, which is stunted. Abnormally bushy looking plants. Terminal shoots curl, yellow and die. Fruit of severely affected plants may darken and die in patchy patterns. Toxicity, yellowing of leaf tips, leading to browning of the leaves.
Calcium deficiency,Thick woody stems, slow growth, yellow upper leaves (not yellow lower leaves seen in N, P or K deficiency), weak, flabby plants. Blossom end rot of fruit. Cure: Correct Ca/Mg balance. Fluctuations seem to bring on blossom end rot. Toxicity, no visual symptoms because it can appear as a plethora of other deficiencies.
Copper deficiency, Stunted root and shoot growth, blue-green curled, flabby leaves, few or no flowers. Bordeaux mixture applied at fungicidal rates will work. Toxicity, reduced growth.
Iron deficiency, Spotted white areas on new leaves and upper parts of stem leading to spots of dead leaf tissue. New shoots may die if severely deficient. Toxicity, Is not usually a problem, but can have possible bronzing of leaves with tiny brown spots.
Manganese deficiency, Very slow growth; light green leaves with dead patches ringed in yellow. Poor fruit development and production with few flowers or fruit. Toxicity, stunted growth, older leaves have brown spots surrounded by a chlorotic circle or zone.
Nitrogen deficiency, Very slow growth of plants, followed by progressive pale green color moving from tip and young leaves back to more mature leaves. Leaves are small, thin, perhaps with purple veins. Stems eventually brown and dry off. Flower buds yellow and drop. Toxicity, dark green leaves with abundant foliage but little root growth or fruit production, flower drop, crops may fail to yield.
Phosphorus deficiency, Stunted plant growth and delay in plant development, purple tinged coloration on leaves, and small leaves that feel fibrous. Fruit set delayed. Toxicity, no recognizable symptoms, however excess phosphorus may cause micronutrient deficiencies, especially iron or zinc.
Zinc deficiency, Very long, narrow, yellowed leaves mottled with dead spots, and interveinal of yellowing on young leaves, as well as reduced leaf size. Toxicity, excess zinc may cause iron deficiency in some plants. commonly accompanied by chlorosis
Typical tomato plant problems
Blossom end rot, See Calcium deficiency above. End of fruit, away from stem gets soft and mushy. Generally caused by a inadequate water availability to the root system, calcium mobilization problems.
Blossom drop, Usually caused by inadequate water availability, and drying winds, but may be caused by sudden cold spells, heavy rains, N overdose, or heavy infections by bacteria or fungi.
Fruit crack, Surface cracks in fruits near stem end caused by rapid growth during periods of good moisture and high temperatures. Cracks can radiate around stem or encircle “shoulders” of tomato. May vary in depth. No cure, but even moisture availability to the root system will help prevent periods of slow, and then rapid growth. Pick fruits with rapidly developing cracks early (not fully reddened) to prevent Early Blight and other fruit rots.
Leaf roll, Rolling begins on lower leaves and proceeds upwards until most leaves are affected. Plants may lose leaves, particularly on staked plants. Seems to be caused by heavy pruning or deep, close cultivation.
Sunscalding, Occurs when green tomatoes are exposed to sun, most commonly in hot, dry weather on plants with leaf spot diseases or other defoliation.
Curly top (western yellow blight), Caused by the same virus as curly top of sugar beets. Seems to be carried by beet leafhopper. Main symptoms are curling and twisting of leaves of affected plants. Prevention is planting at times that may avoid high leafhopper populations, or excluding insects with row covers.
Useful Links
Color Pictures of Mineral Deficiencies in Tomatoes
Plant Nutrition
Emerging Virus Diseases of Greenhouse Vegetable Crops
Symptoms of Deficiencies and Toxicities by Element
Nutrient Functions and Deficiency Symptoms (25 page pdf.)
