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Plant Diseases/trunk damage with white barnicles


QUESTION: I have a 10 year old maple tree probably 18 to 20' tall and I've noticed the on one side the bark is cracking in places and completely gone in other. I just noticed there are these white barnicle looking things on the bare spots and also in the cracks of the bark.  The affected area is about 24" tall and about 6 to 8" wide and starts maybe 6" above the ground.  Other than this the tree looks healthy and growing.  I tried to pull off all the dead cracked bark and scraped off all the barnicles. What do I need to do to correct this?  I don't want to lose the tree.

ANSWER: Cracks and splits in tree trunks are fairly common and may occur for various reasons, but are usually not a significant threat to the tree. Typically, there's not much you can do about them once they occur.

One of the most common reasons for cracks and splits on tree trunks is frost cracking. Frost cracks occur during cold winter weather. The inner and outer wood in a tree's trunk expands and contract at different rates when temperatures change. When winter temperatures plummet below zero, especially after a sunny day when the tree's trunk has been warmed by the sun's rays, the different expansion rates between the inner and outer wood can cause such a strain in the trunk that a crack develops. Frost cracks occur suddenly, can be several feet long, and are often accompanied by a loud, rifle-shot sound. Frost cracks at a point where the trunk was physically injured in the past.

Maples and sycamores are very prone to frost cracks. Apples, ornamental crabapples, ash, beech, horse chestnut, and tulip trees are also susceptible. Isolated trees are more subject to frost cracks than trees in groups or in forest settings. Trees growing on poorly drained soils are particularly prone to frost cracks.

Frost cracks often close during summer, only to re-open in succeeding winters. They do not seriously damage trees, although they do provide openings where certain disease organisms may enter the tree, particularly if the tree is in a weakened condition. Frost cracks are difficult to prevent. Wrapping the trunks with tree wrap paper in fall helps, but is inconvenient to do year after year. Apple growers sometimes white-wash the trunks of apple trees to prevent frost cracks and other winter injury problems, but this is unattractive in landscape settings. The best way to prevent frost cracks is to prevent any injuries to the trunk throughout the tree's life. A professional arborist can bolt frost cracks shut with a technique called lip bolting. Most people simply remove loose bark hanging along the edges of the crack. You should not paint frost cracks or other wounds with tree wound dressing. These materials can trap moisture, causing decay in the trunk.

Sunscald is another form of winter injury that can cause cracks and splits. Sunscald occurs when cells in the living tissue beneath the bark thaw out on sunny days. This occurs mainly on the south or west side of trunks and branches. These cells rupture when they re-freeze at night. The tree is injured when enough cells in a given area rupture. You'll notice the injury the following spring as a discolored, sunken area. Fungus infections often invade trees via sunscald injuries. Young, thin-barked trees are most susceptible to sunscald injury. These include maple, honey locust, linden, and mountain ash. Heavy pruning on neglected trees exposes sections of bark that have been protected from the sun's direct rays for years, predisposing them to sunscald injury.

You can reduce or eliminate sunscald injury on young trees by wrapping the trunks each fall with tree wrap paper. Do this every year until the bark begins to roughen. This may take only a few years on some trees, but more years on others. Prune trees that haven't been pruned for years in stages, not all at once. This will help prevent sunscald.

I would spray the area with an insecticide called Merit to prevent borers from entering the trunk. And fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good. This will increase the health of the tree and allow the tree to better stave off any insect or fungi.
In general I would not be too concerned about the crack except for borer prevention.  

The "barnacles" sound like lichens. These ate a combination of fungi and algae. They are not a problem on hardwood trees and are normal. No need to treat them.

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damaged tree trunk
damaged tree trunk  
QUESTION: I attached a picture of the tree.  Can you tell if this is from frost crack or sunscald?   The damaged area is facing the Southwest and it's in Oklahoma where we have really hot summers.  Also what do you recommend that I do to repair this?

This looks like sunscald. But it has been damaged some time ago. There is evidence of the tree trying to seal over the wound. The callus raised tissue along the edges is the new cells growing toward the center of the wound. What is exposed is the woody cells. These are dead. A tree has living cells just under the bark and they lay down new cells outward and the old cells are the wood of the tree trunk. The bark protects the wood from borer and fungi entering the trunk. The insect borer is the worst since it can kill the tree. The evidence of borer activity is holes drilled into the wood and sawdust from the boring. I can not see any of this. The fungi will enter the wood and is called a decay fungi. This will Not kill the tree but can hollow the trunk and make the tree trunk weak and it could break off. The hollowing by the fungi will take many, many years and if the wound heals over it will not be a problem. I see a little of this decay activity.

The borers can be prevented and kept out by the use of an insecticide. There is a product called Merit that if sprayed on the wound will protect the trunk from borer damage. Bayer Advanced has Merit insecticide in it. I would treat the tree now and again in the early spring and again in mid summer.

The decay fungi can not be treated with a fungicide. The best way to deal with this is fertilize the tree and cause it to grow faster and the tree over time will seal off the wound. Fertilize now and again in the early Spring.  Leave the loose bark around the wound alone it will slough off by it own. Do not damage the growing callas cells around the wound.

So what to do --Spray the wound with insecticide for the prevention of borers and fertilize the tree to increase the health and growth.  

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Jim Hyland


30 years experiance in the ID and management of forest diseases and ID of landscape tree diseases.

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