Iron chlorosis is a disease in plants caused by an iron deficiency. There are a number of techniques which can be used to address and prevent this problem, and as long as iron chlorosis is treated early, plants do not usually experience any long term effects. Because nutrient deficiencies are an important concern for plants, it is important for gardeners to test their soil so that they know which nutrients their plants can access, and to amend the soil accordingly to prevent deficiencies.
In iron chlorosis, a plant is not absorbing iron from the soil. This can be because the soil lacks iron, or because the soil is highly alkaline, in which case the plant has difficulty pulling the iron from the soil. The lack of iron inhibits chlorophyll development in the plant, causing the leaves to start to turn yellow. Iron chlorosis usually starts in one area and slowly spreads. It is highly noticeable, with the leaves first yellowing and then dying.
If the condition is left untreated, eventually the entire plant will yellow and die off due to the iron deficiency. The most rapid treatment option involves foliar spraying of an iron solution, so that the tree can absorb iron directly through the leaves. However, this will not address the long term issues with the nutrient balance in the soil, making it important to take additional steps.
If the soil has not been tested, a sample should be taken so that it can be examined. If the soil has a relatively neutral pH, gardeners can simply add iron-rich amendments to the soil so that the plant can access the necessary iron. If the soil is alkaline, they will need to make the soil slightly more acidic to free up the iron in the soil for the plant's benefit. Another option is to use plants which are adapted to alkaline soil, as these plants tend to be more adept at getting and using iron.
Some other factors can influence the development of iron chlorosis. Poor air circulation in the soil is often a big issue, and it can be caused by waterlogging of the area around the plant, the use of plastic covers over the soil, or tightly packed soils which are not properly aerated. Aerating the soil and addressing drainage issues can help with these problems. Persistent cold temperatures can also promote the development of iron chlorosis, especially in plants which are not accustomed to such temperatures.