Hello Nada,

Michigan‑specific, .edu‑grounded breakdown of the main bark concerns on maple trees and how each is treated.

REFERENCES:

Maple Disease

What's wrong with my plant? : Garden : University of Minnesota Extension

Winter Injury and Frost Cracking

Ask Extension - maple tree bark cracking and peeling (Horticulture & Gardening)

Major Bark Problems on Maple Trees in Michigan

1. Cankers (fungal or bacterial)

This is the most common serious bark issue on maples.

“White to buff‑colored fungal growth may be seen around outer portions of expanding canker if bark is removed”

“There are also cankers – sunken dead areas…”

Symptoms

Sunken, dead bark patches

Cracked bark around the lesion

Branch dieback above the canker

Sometimes fungal growth at the margins

Treatment

Prune out affected branches 6–12 inches below visible damage

Sterilize tools between cuts

Improve tree vigor (mulch, water during drought)

Avoid wounding the trunk

Severe trunk cankers → arborist evaluation

2. Frost Cracks / Winter Injury

“Winter Injury and Frost Cracking… new growth is more susceptible to splitting”

Thin‑barked maples are especially vulnerable

Symptoms

Long vertical cracks on the trunk

Bark splitting after freeze–thaw cycles

Sometimes accompanied by oozing sap

Treatment

Do not fill or seal cracks

Maintain tree vigor

Mulch root zone

Avoid late‑fall fertilization (promotes tender growth that cracks)

Young maples can be wrapped with tree guards in winter

3. Bark Chewing / Removal (animals or mechanical damage)

“Maple > Trunk/Branches > Bark chewed or removed”

Lightning can also cause bark removal

Common causes

Squirrels

Rodents (especially in winter)

Deer rubbing

Lawn equipment injury

Lightning strike

Treatment

Protect trunk with hardware cloth or tree guards

Avoid mower/weed‑trimmer contact

For small wounds: allow natural callusing

For large girdling wounds: arborist evaluation (may require bridge grafting)

4. Root or Fill Damage Leading to Bark Decline

“As little as 4 to 6 inches of fill can be damaging to some maples…”

Symptoms

Bark dieback near the base

Reduced vigor

Early fall color

Crown thinning

Treatment

Remove excess soil if possible

Improve drainage

Mulch lightly (not deeply)

Water during drought

Long‑term monitoring

5. Fungal Decay at the Base

“Thick black, shoestring‑like fungus… under the bark, around roots…” (classic Armillaria symptoms)

Symptoms

Mushrooms at the base

Bark sloughing

Soft, decayed wood

Shoestring‑like black fungal strands under bark

Treatment

Unfortunately, no chemical cure

Improve vigor

Reduce soil moisture around trunk

Remove tree if structural stability is compromised

How to Tell Which Problem You Have

Look for these clues:

Sunken dead bark → Canker

Long vertical cracks → Frost crack

Chewed bark → Animal damage

Mushrooms or black strands under bark → Root rot

Bark dying near soil line after adding fill → Root suffocation

AND YOUR BARK HAS LICHENS WHICH ARE HARMLESS!

Bottom Line

Michigan maples commonly experience:

Cankers

Frost cracks

Animal damage

Root/fill injury

Fungal decay at the base

Most issues are manageable with pruning, protection, and improved tree care. Only root‑rot‑related decay lacks a curative treatment.

PLEASE GET A CONFIRMED DIAGNOSIS FROM THE MSU PLANT AND PEST DIAGNOSTICS LAB

I highly recommend you send all your images by e-mail to the MSU Plant & Pest Diagnostics Lab to get a confirmed diagnosis on your Maple trees

Their email is <personal data hidden>. Please include your first and last name.

The experts there can also recommend the best treatment options.

The lab will let you know if they need a sample sent.

The lab may also ask for additional images. So be prepared.

Their website is at this link:

Plant & Pest Diagnostics (msu.edu)

Their Contact Information is at this link:

Contact Us - Plant & Pest Diagnostics (msu.edu)

This link will explain the details on submitting a sample to the MSU Plant & Pest Diagnostics Lab:

Submit Samples - Plant & Pest Diagnostics (msu.edu)

I hope this helps!