Chlorosis

Chlorosis is a general term for foliage that is not producing adequate chlorophyll. This leads to a yellow or pale appearance. The lack of chlorophyll means that the plant's most important process is being interrupted. If not corrected, chlorosis will lead to dieback of branches and eventually the entire tree. Chlorosis generally is caused by a lack of iron, but it may also be caused by a deficit in other micronutrients as well. Iron is present in most Colorado soils but due to low pH it cannot be absorbed by the trees.

How Can I Identify Chlorosis in My Trees?

Chlorosis is a major problem with maple and oak trees in Colorado, although many other species can also be affected. The signs of chlorosis are any leaves or branches in the tree with inconsistent color. Parts of the tree may appear lime green while other parts are a deeper green. In advanced stages leaves will turn yellow and almost white at times. If you look at a leaf and the veins are darker green but the rest of the leaf is lighter in color - that is chlorosis.

Deep Dark Green Color

This is a healthy leaf with all the micronutrients it needs
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Slight Chlorosis

This leaf is slightly chlorotic but if your tree has leaves like this you likely just need to add some organic material into your soil and just work on building healthier soil.
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Serious Nutrient Deficiency

If your leaves are this color your tree is seriously lacking in nutrients and the tree could probably use mincronutrients spread over the soil.
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Very Chlorotic Leaf

When a tree's leaves are this pale yellow color it is a sign of major deficiencies. This is when I would reccomend an injection of micronutrients directly into the base of the tree.
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Causes

The main cause of iron unavailability in soil is low pH. Colorado's clay soil is too alkaline, which causes iron to oxidize in the soil and form insoluble compounds which cannot be absorbed by tree roots. The obvious fix would be just to change the pH of the soil, but due to the buffering capacity of the soil that is near impossible. Buffering means that the clay (which makes up most of the soil in Colorado), will react quickly with any acid that is introduced and will not result in any change to the soil pH. The only solution is to replace or amend all of the soil under your tree. But this is just not feasible in a well established landscape.

Chelated Micronutrients

Since we cannot change the properties of the soil quickly enough to help trees that are already stressed, the only solution is to give them what they need. Chelated micronutrients have metal ions locked up in compounds that are stable in the soil. There are many different chelates for each micronutrient and their stability in soil varies greatly. Using the wrong chelated fertilizer won't work because if it is not stable in the soil it will just react and wash away.

Leibig's Law of The Minimum

This is a principle that states that plant growth will be limited by the micronutrient most deficient. This means that even if a deficient micronutrient is added, plant health will only be improved to the point that another micronutrient becomes the limiting factor. This is important when treating chlorosis because even though the iron may be available to a tree, if there is not enough manganese the tree will still not fully green up. For this reason it is advisable to supplement soil with all micronutrients that are less available in alkaline soils. The nutrients we advise you use are iron, manganese, and zinc.

Selecting Which Chelates to Use

Because certain chelates are more stable in alkaline soils it is very important to select the right one. Here is the list of the chelates that we recommend:

If you just get chelated micronutrients from the local retailer, it will likely not include the proper chelates and they will not be as effective. These micronutrients are specially formulated for use in soils like ours.

Iron (Fe) EDDHA

https://www.amazon.com/Grow-More-6546-Chelate-1-Pound/dp/B00BWE2CUE/

Manganese (Mn) EDTA

https://www.greenwaybiotech.com/products/chelated-manganese-edta

Zinc (Zn) EDTA

https://www.greenwaybiotech.com/products/chelated-zinc-edta

These can be spread directly onto the soil. Soil treatment should occur in the spring before the tree leafs out.

Moderately Chlorotic Maple

When a tree is this level of chlorotic the first step should be to spread micronutrients on the soil. If this is ineffective injections may be necessary.
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Highly Chlorotic Maple

When a tree has branches dying back from chlorosis injection is likely the best course of action. Branches dying back mean that permanent damage is occuring and should be adressed immidiately.
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Severely Chlorotic Maple

A tree at this point has already sustained serious damage and may not fill out properly again. These trees can still be helped with injections if the owner decides they want to try to save it.
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Trunk Injection

Directly injecting micronutrients is a more reliable method to get nutrients into the tree. This requires drilling holes into the tree. Drilling into the tree should be considered a last resort and only for trees that are too far into decline or where adding nutrients to soil has not been effective. This requires specialized equipment and must be done by a tree care professional. Trunk injections should occur in the fall just before the tree loses all of its leaves.

Stay tuned and follow us on Facebook for more articles on tree care.

Chlorotic autumn blaze maple

This tree is slightly chlorotic and is experiencing some dieback which you can see on the left side of the tree
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Chlorotic foliage

You can see the veins are deep green but the leaves are slightly chlorotic
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Chlorotic foliage

You can see the veins are deep green but the leaves are slightly chlorotic
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Micronutrient injection

This is how we do trunk injections
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Related Projects

We have used them twice so far because of the great work they did the first time. They did exactly what we needed done to our trees, and when they are done, they leave the yard as clean or cleaner than when they had started.

Kristi M. (Lafayette, CO)

MashIt
Did a great job of removing trees without damage to surrounding plants. Did a great job of cleaning up afterwards. Very satisfied.

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"Lucas was timely, honest and super helpful. He didn't try to sell me any services other than what I called about, which I greatly appreciated. I'll definitely be using him again for pruning trees in the winter."

FabuFit
Lucas and his team were true professionals They were courteous, really knew what they were doing. Fun to watch! They cleaned up afterward, the whole yard even though their debris didn't cover the whole yard! Very reasonable pricing also. Highly recommend

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They were efficient, did a great job quickly and cleaned up the yard afterwards. Couldn't ask for more. Highly recommended.

YesSuits
" They were able to come in and grind down the large Cottonwood stump and remove the debris in a reasonable amount of time. Very pleased with their service and pricing that we hired them to remove another Cottonwood from our backyard."

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Foothills Arborists

Lucas Capachin

Board Certified Master Arborist RM-7913B

(720) 600-2745 Luke@FoothillsArborists.com

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Chlorosis

Deep Dark Green Color

Slight Chlorosis

Serious Nutrient Deficiency

Very Chlorotic Leaf

Moderately Chlorotic Maple

Highly Chlorotic Maple

Severely Chlorotic Maple

Chlorotic autumn blaze maple

Chlorotic foliage

Chlorotic foliage

Micronutrient injection

Related Projects

We have used them twice so far because of the great work they did the first time. They did exactly what we needed done to our trees, and when they are done, they leave the yard as clean or cleaner than when they had started.

Did a great job of removing trees without damage to surrounding plants. Did a great job of cleaning up afterwards. Very satisfied.

"Lucas was timely, honest and super helpful. He didn't try to sell me any services other than what I called about, which I greatly appreciated. I'll definitely be using him again for pruning trees in the winter."

Lucas and his team were true professionals They were courteous, really knew what they were doing. Fun to watch! They cleaned up afterward, the whole yard even though their debris didn't cover the whole yard! Very reasonable pricing also. Highly recommend

They were efficient, did a great job quickly and cleaned up the yard afterwards. Couldn't ask for more. Highly recommended.

" They were able to come in and grind down the large Cottonwood stump and remove the debris in a reasonable amount of time. Very pleased with their service and pricing that we hired them to remove another Cottonwood from our backyard."

Foothills Arborists

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