In some areas vegetation from the entire landscapes may be affected, while in others only the most susceptible plants show deficiency symptoms. Any reduction in chlorophyll during the growing season can reduce plant growth and vigor. In addition, chlorotic plants often produce smaller fruits of poor quality with bitter flavor. In severe cases, or if iron chlorosis persists over several years, individual limbs or the entire plant may die. The causes of iron chlorosis are complex and not clearly understood.
Many reactions govern iron availability and contribute to the complexity of iron chemistry in soil.
At high soil pH, iron rapidly forms solids in combination with oxygen, and hydroxide and carbonate ions. These forms of iron are not water-soluble and cannot be absorbed by plant roots. Such iron will be tied up indefinitely unless soil conditions change. Chlorosis is often more severe where topsoil has been removed exposing lime-enriched subsoil. Examples are eroded soils or soils subjected to land leveling for agriculture irrigation or new housing developments.