Does something just not look right about your tree this summer? Are the leaves starting to turn a little yellow? Are the veins of the leaves the only portion that is green? Are the leaves falling off prematurely? Are these signs happening on a isolated branch or the entire tree? If any or all of theses symptoms are present, you have high likelihood of iron chlorosis.

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Chlorosis is a very common nutritional disorder in many trees in our area of Wisconsin. Some of the most likely trees to have chlorosis in our area include silver maple, red maple, white oak, paper birch, and river birch.

Chlorosis is a condition where the tree is unable to efficiently produce chlorophyll. Chlorophyll is a vital leaf component which is responsible for energy absorption for trees. Trees without enough chlorophyll will not be able to grow and thrive.

Iron and manganese are the common micro-nutrient deficiencies that cause chlorosis in trees. These minerals are often not lacking in the soil, rather a condition exists where the tree’s root system is unable to obtain them in usable forms. Poor absorption of micronutrients is common in Wisconsin because of the high pH (alkalinity) of many soils (pH greater than 6.5).

There are several treatment methods available for us to treat chlorosis. Remember, it is important to determine what is the cause of the chlorosis first.


Soil injected fertilization with added micronutrients can help increase the amount of iron in the soil. Fertilization is best done in the spring or fall. 

Trunk Injection:

If iron is available in the soil but the pH is too high, trunk injections of iron can be done in one year or three year dosages. One year dosages of iron can be done anytime of year while the three year dosage needs to be done in fall.

Growth Regulator:

Trees treated with paclobutrazol, which is an active ingredient, show an increased production of fibrous roots. This helps the plants by expanding the area of soil the plants can pull water, minerals, and other resources from. This treatment is applied to soil and may be applied anytime that this ground is not frozen or saturated with water.

Soil Remediation:

The primary goal is to create a suitable soil environment that promotes fibrous root growth resulting in greater capacity to acquire water and nutrients from urban soils and a healthy more vigorous tree.

Compressed air is used to reduce soil compaction, increase oxygen in the soil, and incorporate organic matter into existing soils. This treatment increases the likelihood of improving the soil structure and establishing a beneficial for tree root growth.

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written by:

Fred Hoppe
Board Certified Master Arborist WI-0556B
Hoppe Tree Service