Chlorosis

Chlorosis is a common problem of urban trees that struggle to make chlorophyll and therefore turn yellow.

Chlorosis is a serious condition where a tree’s ability to manufacture chlorophyll has been compromised. Chlorophyll is the pigment that plays a vital role in the conversion of the sun’s energy into sugar, which is used by trees for all metabolic processes including growth and defense. The lack of chlorophyll will result in a weakened tree that is susceptible to opportunistic insects that can kill the tree.

Download Chlorosis Fact Sheet

Treatment Strategy

The long term goal of managing chlorotic trees is to establish sustainability, a condition where a tree can exist without chlorosis and without the need for further inputs.

One of the major causes of chlorosis is a compromised root system, so restoring the roots as well as providing nutrients for chlorophyll production will deliver the best results. Effective management strategies for chlorosis include: using Verdur® or Verdur® MN to increase chlorophyll production, wood mulching to create good soil conditions for root development, and stimulating fibrous roots using Cambistat®.

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Chlorosis Treatment Option 1

Utilizing Verdur® to Increase Chlorophyll

Depending on the type of tree being treated, Verdur® and Verdur® Mn are tree infusion products that will quickly restore the tree’s ability to make chlorophyll and absorb energy. Verdur® Fe restores green color for approximately three growing seasons and Verdur® Mn for approximately two. Common trees to use Verdur® Fe include oak, birch and most other trees. Use Verdur® Mn on maples.

Application Type Low Volume Macro-Infusion

DIY Product/Equipment Needed:

•  Verdur® or Verdur® Mn

Low Volume Macro Infusion Pump Kit

•  Shovel or trowel

•  Drill (with high helix drill bits)

 • Stiff-bristled hand brush

•  Gloves

•  Safety glasses

Chlorosis Treatment Option 2

Stimulating and Maintaining a Healthy Root System

The second step of treatment involves helping the tree re-grow its root system and provide a healthy root environment. Putting a 3″ deep mulch ring around the trunk of the tree will help keep roots moist and increase its fibrous root system. The optimal size for a mulch ring is one foot for every inch of trunk diameter. However any size mulch ring is beneficial.

Chlorosis Treatment Option 3

Controlling Growth with Cambistat®

The third step is to use Cambistat® (a growth hormone regulator) to control growth by favoring root development over top growth, which will further stimulate root growth, according to university research. A more expanded root system equates to a healthier, greener top and a significant increase in drought tolerance.

Application Type – Soil Drench

DIY Products/Equipment Needed:

•  Cambistat®

•  Soil Drench Kit

•  Measuring or Diameter Tape

•  Shovel or trowel

•  Graduated cylinder measuring in mL

•  Bucket or watering can

Chlorosis DIY Kit

Step 1

Application Type  Low Volume Macro-Infusion

DIY Product/Equipment Needed:

•  Verdur® or Verdur® Mn

•  Low Volume Macro – Infusion Pump Kit

•  Shovel or trowel

•  Drill (with high helix drill bits)

•  Stiff-bristled hand brush

•  Gloves/safety glasses

Step 2

Application Type – Cultural practices

DIY Products/Equipment Needed:

• Mulch

• Shovel

• Rake

Step 3

Application Type – Soil Drench

DIY Products/Equipment Needed:

•  Cambistat®

•  Soil Drench Kit

•  Measuring or Diameter Tape

•  Shovel or trowel

•  Graduated cylinder measuring in mL

•  Bucket or watering can

How Is It Spread?

Poor soil conditions primarily lead to problems with chlorosis.

Susceptible Trees

Commonly affected tree species include maples, pin and white oaks, river birch, tulip tree, sweet gum, bald cypress, magnolia, and white pine.

Although these are the most common species to have chlorosis problems, just about any tree can have difficulty manufacturing chlorophyll
and become chlorotic.

Symptoms

• Overall yellowing of the tree

• Yellowing in between veins on newer foliage.

• Dead areas developing on chlorotic leaves.

• Tip dieback and decline.

Lookalikes

None

Related/Similar Problems

Drought, stem girdling roots, insect damage

Timing

Fall

Urgency

High

Risk of Spreading

Moderate

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