Leaves of plants deficient in nitrogen turn uniformly yellow; stems and petioles may redden. Both old and new leaves are affected. Leaves deficient in zinc may show chlorosis in between veins, mottling, and crinkling of leaves. Deficiency of iron causes overall yellowing leaving green veins.
Solutions
Provide adequate fertilizer and follow other recommended cultural practices. If you apply fertilizer during the season, be sure to use only the minimum amounts needed to avoid potentially harmful accumulations of salt. In lime or alkaline soils, do not apply iron salts to the soil to correct deficiencies in iron. Most alkaline or lime soils can bind iron very tightly causing the iron to become unavailable for many plants, resulting in an iron deficiency. Applying iron to the foliage in the form of a "chelated" liquid iron is the best way to manage lime-induced chlorosis. Chelates need to be applied frequently and are best applied to the young expanding leaves in spring. In some cases, adding sulfur to the soil may help to drop the pH and allow the iron to become more available to the plants.
