How to Cure a Tree with Chlorosis

How to Cure a Tree with Chlorosis


Chlorosis is a serious tree problem in the Treasure Valley, especially with our clay and very alkaline soils. Chlorosis is a lack of available Iron in the soil. Which leads to your tree losing the ability to make enough chlorophyll to support itself through photosynthesis. Without chlorophyll, a tree cannot produce the energy and sugars that it needs to grow and even survive.


Many studies have been done on this problem and the most common reason for a tree to show signs of chlorosis is attributed to the pH of the soils. Ada County and the surrounding areas are on average an 7.5 to 8.0 on the pH scale, which is very alkaline. When you reach high pH, it ties up Iron in the soil and does not make it available for the tree to absorb it, thus the tree becomes deficient in the nutrients that it requires rebuilding its chlorophyll.

Another study that was done, but has not yet been completely proven, is that a poor root structure might also be a cause to a chlorotic tree. Adding Mycorrhizal fungi (which is a beneficial fungus) to the soil and increasing the fibrous roots has shown some improvement in the appearance of the trees.

Mycorrhizal fungi have a symbiotic relationship with the plant. The fungi bonds with the roots of the plant to help it draw in nutrients that it might be struggling to get. In return, the plant feeds the fungus the sugars that it produced through photosynthesis. It’s a win-win situation.

Compacted Soil

Determining if the soil is compacted is also very important. If the soil is too compact, it is hard for water and oxygen to get down to the roots and will make it very hard to wash any beneficial nutrients down there or to get a soil acidifier into the root zone. All of those are very important for healthy root growth. Getting some organics worked into the soil, like a good compost that is not high in salts, will definitely help to break up clay and get more air space into the soil.

Zamzows offers many products that can help you correct chlorosis in trees. Magic Mineral is packed full of Iron and other micronutrients that are essential to tree health.

Zamzows carries many soil acidifiers, some with iron and some without, both are good in lowering your pH. You can also use straight sulfur, which will also help lower your pH.

Zamzows Thrive will also help make nutrients bio-available so whatever you apply is usable by your trees.

Zamzows Huma Green is another product that is primarily applied to our lawns. However, its high Iron content is perfect for our trees as well. Applying an extra application of Huma Green can greatly benefit many of your trees and shrubs in your landscape.

Important reminder

Iron Chlorosis is not a one-time treatment for full recovery. This process will take a number of seasons to fully correct. Once you have seen recovery you will need to continue treatment to prevent future decline. It is also important to note that you won't see a lot of recovery at the time of application. Trees will only take up Iron in the spring so you won't see anything happen until the following spring.