What is Chlorosis?

Chlorosis is a nutritional disorder of plants in which leaves are unable to produce sufficient chlorophyll. The problem occurs when the plant is deficient in one or more micro-nutrients, especially iron, manganese or zinc. Without these essential nutrients, the plant is unable to manufacture enough chlorophyll to maintain its health. The nutrients may be missing from the soil, or they may be present but the plant is unable to absorb them through its roots. Possible causes of poor root absorption include damaged or compacted roots, poor soil drainage, high soil alkalinity, insufficient soil fertilization or poor root growth.

The symptoms of chlorosis are easy to identify and include yellow to whitish-yellow leaves with green veins, stunted growth and the inability to produce flowers and fruit. The entire plant or an isolated area may be affected. Trees, shrubs and plants of all kinds may develop the condition, but oaks, pines and maples are more susceptible than others. In severe cases, leaves turn brown and drop off, and the entire plant may die of malnutrition.

In order to treat chlorosis, the lacking nutrient must first be identified. Iron deficiency chlorosis begins on younger leaves and moves inward toward the older leaves. Manganese and zinc deficiency chlorosis, however, begins on the inner, older leaves first and progresses outward toward the newer leaves. A soil test may also be performed to help diagnose which nutrients could be deficient in the soil. Once identified, the proper nutrients can be introduced to the soil for the plant to absorb, or applied via a trunk or foliar application if root absorption is a problem.

Foliar applications consist of spraying the affected leaves with the necessary nutrients in water-soluble form. This remedy, however, only treats the leaves that are present at the time of application and several applications may be necessary throughout the growing season. Trunk applications consist of drilling several holes in the trunk of an affected tree and inserting tubes, which are also inserted into containers of liquid nutrients. The tree naturally draws the nutrients into its trunk and once the containers are empty, the tubes are removed and the holes in the trunk plugged.

Although chlorosis can kill a plant, it is rarely fatal if the condition is treated properly. The problem can be prevented by testing the soil before planting and amending with the proper nutrients as necessary, planting trees, shrubs and plants that are not susceptible to the disease, avoiding unnecessary pesticides and monitoring plants closely for tell-tale signs of chlorosis such as yellowing of leaves. Treating plants as quickly as possible will extend their lives and prevent the loss of foliage.