Potassium influences plant growth, and nutritional balance of the plant. Deficiencies can be induced by heavy applications of other nutrients such as calcium. The yellow areas coalesce and become necrotic followed by downward cupping of the leaf margins. The dead tissue may shred and give the leaf a ragged appearance. Severely deficient plants produce wrinkled or misshapen seeds.
Some cultivars show leaf hopper injury that mimics potassium deficiency.
Potassium deficiency can be corrected by applying fertilizers that contain potassium. A soil test should be used to determine the correct amount of potassium to apply. 31 Manganese Toxicity Manganese is important in respiration and nitrogen metabolism. Manganese toxicity is common on light soils in the southeastern United States, and usually occurs when the soil pH drops below 5.0. In severe cases a brownish orange necrosis may develop along the leaf veins.