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The Greener View: Tree Lichens

Jeff Rugg on

Q: I have a spruce tree that used to be perfectly shaped. The very top of the tree trunk has been broken off. I think a hawk that stays in our area tried to perch on it and broke it. I don't know what to do for the tree. Will it grow a new straight trunk on its own? Or should I tie one of the lower branches to grow upward and take its place? And how do I keep the bird away?

A: I wish I had a hawk to watch in my yard, but I wouldn't want it breaking my tree.

The top buds on the tree trunk release chemicals that prevent other buds from growing. This is called apical dominance, and it is pretty strong in trees that are the typical cone shape of a Christmas tree. It is weak in trees that have a round silhouette. When that bud is lost or damaged, the other buds are released from dormancy. The top of your tree may start growing several new "leaders" (as the top section of a tree trunk is called). This is not good as they are usually weak, and an evergreen tree with more than one trunk is more likely to split in a storm.

If there is a straight branch that you can pull into an upright position, then do it. You will need to tie a stick or pole to the trunk several feet below the branch in several places. The pole will need to stick up higher than the new straightened branch, which will need to be loosely tied to the pole in several places. The tying is necessary so the pole stays in place. It should be done in such a way that the ties can be loosened as the trunk and branch increase in girth.

The branch should not be tied too tight; it must be allowed to flex and sway so that it builds strength on its own. If tied too tightly, it will weaken like a leg struggling to heal in a too-tight cast.

Try taking the pole off next spring to see what the new leader does. If it starts to flop over, reattach the pole for another few months.

Using a thin but sturdy pole several feet taller than the branch may not allow enough of a grip for the hawk to hold on to.

 

Q: My problem is with new maple trees. They have smooth bark that is not rough like you might expect on a tree trunk. There are two-inch diameter circular spots of yellow and white that almost look like they are tattooed on the bark. The trunk looks sick. I think they started about midsummer. Should I be concerned? How can I wash them off without hurting the tree trunk?

A: It sounds like your tree's trunk is covered with lichens. They are often the bright yellow-green "stain" visible on a tree's bark. They are a combination of an alga and a fungus and are common on tree trunks and rocks. There are many species of lichens. Some are just the stain you are seeing, and some have raised areas that look like leaves. They can be any color.

They are absolutely no problem to the tree. Sometimes people think they are the cause of a tree's problem, but they are not. They may have been dormant and not too colorful, so you didn't notice them until midsummer. They are usually slow growing, so lichens two-inches in diameter have been on the tree for longer than this summer.

There is no reason to do anything about them, and I wouldn't try washing them off.

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Email questions to Jeff Rugg at info@greenerview.com. To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

 

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