Deficiencies can cause foliage to discolor, fade, distort, or become spotted. Fewer leaves, flowers, and fruit may be produced, and these may develop later than normal and remain undersized. Commercial laboratories can conduct foliage tests or soil analysis to verify deficiencies. Typical symptoms vary among vegetable species.
Nitrogen-deficient potato plant
Older leaves are yellowish; new growth sparse, undersized; plants grow slowly and foliage may drop
Zinc-deficient potato
Leaves are yellow or purplish; new growth may be stunted or delayed, small or narrow
Phosphorus-deficient tomato
Seedlings grow slowly and have purple leaves; symptoms seldom appear on mature plants
Iron-deficient tomato
New foliage is small and yellowish, although green along veins; dead spots may develop between veins or on leaf tips.
Potassium-deficient tomato
Leaf tissue between the main veins turns yellow while the leaves remain green; leaves may roll and edges may burn
