Apparently, this is a common question!
A while back, I wrote part one of this barky topic. It reviewed how tree bark developes and how the cracks and fissures are a non issue. Since then, we have gotten tons of questions about why large chunks of bark fall off trees. I had two 60-year-old trees do this, in my yard. Both were eventually cut down. Most people only notice the problem, after the bark falls off. Trust us, it almost never happens over night. The problem has festered for a while and you finally saw it. Waiting to see if it heals itself is a macro-economic mistake, especially on a large valuable tree. There is no cut and dry answer to why bark falls off a tree. There could be multiple reasons and many answers. Insects, disease, drought, excessive moisture and even mechanical damage. Figuring out whether you need a professional arborist to treat the tree or someone to cut it down, is a challenge. To decide, let’s look at some things you can do.
Your First Clue
We usually notice the problem when we see a secondary problem…ants. If it’s a “one ant here, one there thing”, it could just be that they are foraging, looking for a meal.
The picture above is from a couple in Arlington, TX. They noticed the damage to the bark and when the loose bark pulled away, the space under was full of ants. They treated and killed the ants. The ants are a secondary problem…a symptom of a bigger issue. The ants took advantage of a dry cavity. This particular problem was diagnosed by an arborist. It was from excessive moisture caused by the ground cover and the sprinkler system. The crown (where the trunk meets the root system) of the tree never dried and never saw the sun light. The home owner removed the surrounding ground cover and adjusted the sprinkler system.
Disease (Dramatic music…Beethoven’s 5th Symphony comes to mind)
Disease comes in 3 different types; fungus, bacteria and virus (which are rarely an issue). Fungus and bacteria are advantageous problems. They take advantage of environmental conditions that benefit themselves and that place stress on trees and plants. Just like when we get stressed out and sick, trees and plants can too.
The most common causes of stress on plants are:
Too much water can either be from excessive amounts of rain or sprinkler use. There isn’t much we can do about excessive rain, other than building high, well-drained beds. Unfortunately, most people don’t use their sprinkler system properly. Setting it for X number of minutes, X number of days a week is just unnatural. Does it ever rain for 7 or 10 minutes 3 days a week? Longer times, with a 2nd round an hour later is a more natural and effective way to water. When it rains, it is commonly slow and steady over hours or it comes in bands. Either type of rain fall, allows the ground to absorb a tremendous amount of water. Your sprinkler can mimic rain bands, letting the 1st watering sink in and the 2nd one to sink in deeper. Then allowing the soil to dry out in between watering.
Drought Keep those trees watered during drought conditions. A large mature oak can drink a thousand gallons of water a day…do the math.
Use of Atrazine (the chemical in most Weed and Feeds) Roots absorb Atrazine. It can’t tell the difference between the roots for weeds and the roots of trees or shrubs. It will slowly poison your trees. Magnolias are especially susceptible to Atrazine poisoning. It persists in our environment and monitored by water districts. It causes amphibians to be born deformed (I could go on)…read more in this article.
Excessive use of mulch can lead to many tree problems. The crown of a tree or plant is the area where the roots meet the trunk. This area needs exposure to sunlight and air. Read more about mulching sins here: https://www.rcwnurseries.com/wp-admin/post.php?post=555&action=edit
The phrase “mechanical damage” can cover a wide array of events. This is a truly “it happened over night” situation. For instance, a car runs off the road and hits your tree, as a result, a chunk of bark gets peeled off. Maybe your next door neighbor’s kid decides to re-enact the myth of George Washington cutting down the cherry tree. Add that he was smart enough not to stage the play in his own yard…and since you were not home, your tree fell victim to a dull axe before his mom caught him. How about your lawn guy being mad at his girl friend. He opts to use a weed eater in an abusive way, effectively removing the bark from the base of the tree. Or maybe the deer you though were so cute chose your tree as a scratching post. These types of mechanical damage are usually fixable. Small scrapes should be cut into a vertical oval. By removing any ragged edges, you eliminate places for water, debris and insects to collect. You can stop a problem from being compounded. Large injuries, lightning strikes and car damage are best left to professionals.
Since, I couldn’t find any damaged trees here at the nursery, I looked for a Texas-based website to show a picture of how to cut the damaged bark away, to promote healing, but this one was better…
Your trees are valuable, inspect them.
Trees, like your home are long-term investments. Pest control companies suggest you inspect the exterior of your house at least quarterly (monthly is better and only takes 5 minutes). Why not add a 5 minute look at your trees at the same time? Over time, you will learn what they look like from each side. If something looks weird, take a picture of it. Email it to us (or your local nursery), your tree guy or the Agricultural Extension Office (AEO) in your county. This web site will help you find your AEO https://www.csrees.usda.gov/Extension/. Calling your Extension Service is always FREE and paid for with your tax dollars.