Treating Iron Chlorosis in Trees

At a time in the season when you expect your landscape to be at its greenest, many area trees are yellow and already starting to drop leaves. 

This yellowing of normally green leaves is due to a lack of chlorophyll, a condition known as chlorosis. Chlorophyll is responsible for the green color of leaves and is essential for the tree to produce the food it needs to sustain growth and maintain health.

Chlorotic leaves are by contrast pale green, yellow or yellow white.

As the chlorosis advances, clusters of leaves will take on a scorched look. Chlorosis may show up on one or two branches or the whole tree may be affected. Many factors, individually or in combination contribute to chlorosis. These involve nutrient deficiencies that are directly related to the soil your trees are planted in, including over watering and poor drainage, the use of plastic sheeting as a mulch, heavy, compacted clay soil and high (alkaline) soil pH. Remedies for chlorosis include applying iron supplements in a form the tree can use, as well as improving soil structure and reducing soil pH. 

Iron supplements are available in liquid and granular forms. Chelated iron is not affected by soil pH levels and is more readily available to your trees. The best iron supplement choice is a complex of iron and the chelating agent EDDEHA. These supplements can be applied directly to the soil under the tree; through a series of holes drilled around the drip line; by trunk injection; by foliar application with a sprayer. The method selected depends on where the tree is planted in your landscape. To fix the problem long-term, you have to fix the soil. 

Applying organic materials such as compost, peat moss and humate will improve soil structure and reduce alkalinity. Each of these products is applied to the area under the tree's dripline, three to four times per year. This is easily done if your tree is planted in your lawn.

Put the HuMic down first and water it in. Follow this with a thin (1/8" to ¼") layer of Sheep and Peat or Peat Moss and water in thoroughly. If your tree is surrounded by mulch, you can pull the mulch back past the drip line and follow the same process as above: HuMic, then Sheep and Peat or Peat Moss and water in.  An alternative approach is to drill a series of holes twelve to eighteen inches apart, eight to ten inches deep around the drip line and fill each hole with HuMic and Sheep and Peat and then water in. Repeated applications will improve the soil structure, increase microbial activity and encourage the tree to take up more iron on its own.

Your tree cannot overcome chlorosis on its own. In fact, it will get worse each season until you have to remove it. Understanding and resolving iron chlorosis is complex. We encourage you to stop by the store with a sample of your tree. We’ll verify the problem and help you select the right products to help restore your tree’s health.