Chlorosis is a yellowing of leaf tissue due to a lack of chlorophyll. Possible causes of chlorosis include poor drainage, damaged roots, compacted roots, high alkalinity, and nutrient deficiencies in the plant. Nutrient deficiencies may occur because there is an insufficient amount in the soil or because the nutrients are unavailable due to a high pH (alkaline soil). Usually, iron deficiency is due to lower availability of iron under alkaline conditions, rather than a lack of iron in the soil. Currently Verdur is being used to treat iron chlorosis.
Generally, mild chlorosis starts as a paling, lighter green to lime-green color, of interveinal tissue, whereas a yellow color indicates a more serious condition. In some cases, only part of the plant is chlorotic. Affected areas may be stunted or fail to produce flowers and fruit. In addition, chlorotic leaves are more prone to scorching and leaf diseases. With severe chlorosis, the leaf veins will turn yellow, followed by the death of the leaf, the affected branch may die back, and death of the entire plant can occur.