The first indication of phosphorus deficiency is an over-all stunted plant. Leaves may be unusually dark green at some stages, may have distorted shapes, and may become purple. Lower leaves may turn yellow between the veins. If stunting is suspected, confirm the visual symptom with plant tissue analysis. However, some plants under certain conditions will exhibit deficiency on younger leaves first.
Growth rate is slow, root systems are poorly developed, weak stalks, and lodging often occurs.
Disease resistance is very low. Deficiency symptoms commonly occur on the youngest tissues because calcium does not move within the plant. Root growth is poor, the growing point may die and the roots turn black and rot. Leaf tips will turn jelly-like and die. Blossom-end rot of tomatoes is calcium deficiency.