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You Have Questions? We Have Answers.

May 10, 2012

How do you encourage lower branch growth on a crepe myrtle? Could construction have caused damage to my tree? What is this suspicious looking moldy growth on my dogwood?

When people are out in their yards during the spring, they are usually getting their landscapes ready for enjoyment. They bring out the patio furniture and dust it off. They take out the accompanying umbrellas and cushions and wash them off, preparing them for enjoying warm evenings and weekends relaxing in the backyard. They clean up their landscape beds, ordering and spreading mulch to give everything a fresh look.

During this time, they also get a chance to get close to their plants. That's when they notice if anything peculiar or strange is happening with one of their trees.

Never fear. The Tree Doctor is here! We can help answer these types of questions and suggest some next steps for tree recovery.

Here are a few of the recent questions we've been asked. We hope the answers to these common questions help you as you care for your landscapes this season.

QUESTION: I bought a tall crepe myrtle tree and was wondering if there is a way to encourage a few lower branches to grow on it?

ANSWER: Allow as much direct sunlight to contact the lower portion of the tree by pruning nearby plants.

QUESTION: I have what I believe to be a scarlet oak tree in my front yard that will not grow leaves on one side. I think it may be a result of neighbors doing some sort of construction on their pipes about 20 to 25 feet away from the base of the trunk. The construction might not have been the problem, but I don't know what else it could be. I have no clue what to do, and I'm low on cash and can't really afford a really expensive evaluation, especially if I need to get it removed. I've never dealt with these sorts of matters and would really like to get my tree back to the healthy beauty it once was.

ANSWER: Oaks have straight grain wood. So if the side of the scarlet oak with damage faces the neighbor with construction, then it is possible roots were severed. The tree canopy compensates by shutting down a percentage equal to the root loss. Roots will eventually regenerate and so will the canopy, but the dead branches will have to be pruned. You can also have a qualified arborist examine your trees. There is no charge for estimates.

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QUESTION: Our Honey Crisp apple tree has had the bark skinned at the ground level by a lawnmower that got too close. How can we help it heal or otherwise keep the tree healthy?

ANSWER: The tree will eventually heal on its own. To encourage good health, apply a slow-release, low-burn fertilizer to the soil and water the tree to prevent drought stress. Also, put a ring of wood chips around the base of the tree. This ring of mulch should not contact the trunk. It's there strictly to prevent future mower injury.

QUESTION: Our landscape has a 25-year-old pink dogwood tree that bloomed beautifully and fully until two years ago … flowers were down by half, and this year we have the same results. The bark of the tree has moldy growth.

I cut dead branches out of the tree and there is a lot of new growth. I cannot find a bug in any of the dead wood, but the trunk of the tree seems dark on one side and the bark is unusually rough. I cannot find a tree doctor in our area of New Jersey, and I'd welcome your thoughts and/or advice.

ANSWER: We recommend you send a sample to the plant problem diagnostic laboratory at Rutgers University. Provide samples of leaves/branches where it transitions from healthy to infected. A dead branch would not be helpful. The molds on the bark could be lichens, which are harmless. Identifying the causal agent is necessary to determine control options.

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QUESTION: My neighbor has a garden on the other side of the fence. I have a maple tree 40 feet tall that did not come back this year; it has no foliage. Other neighbors say lady in the back of my property has killed other people's trees and bushes with a nonselective herbicide. The tree is about 15 feet from the fence. Could she have put this herbicide on the roots and killed my tree?

ANSWER: A nonselective herbicide would have to have been sprayed on all the foliage of the maple tree to cause the symptoms. The active ingredient in major nonselective herbicides is deactivated by organic matter in the soil and not root absorbed. Therefore, your tree is most likely suffering from some other issue.

QUESTION: We have a large oak tree with a root that runs across our driveway (dirt driveway) and is exposed. We would like to cut the root because it is a big bump to drive over but we don't want to kill the tree. Can we do this and what is the best method? Thanks!!

ANSWER: A large, healthy tree can tolerate the removal of a single root. Make a single, sharp cut through the root on the trunk side of the driveway. Let it dry out for several months, then excavate by hand to ensure the severed portion is not alive through root grafts. Water the tree to prevent drought stress.

QUESTION: Recently, my mom gave me a 4' tall liquidambar tree. It's a beautiful little tree and as she is quite old I must keep it alive in her honor. She has always been a wonderful gardener. Sadly, I didn't inherit her talent.

Here is some info on the tree: The tree is root bound in a 10-inch pot on a balcony in the San Francisco area. I have a northeast facing balcony so it gets morning sun.

What's the best time to prune it? How do I know when to water? I usually overwater plants. How do I repot it? What size pot should I use? What's the best potting soil or plant food to use? Is there a book I can buy to learn about this pretty little tree? I have never had a green thumb and am terrified I'll kill my little beauty.

ANSWER: Liquidambar trees reach a mature height over 100 feet in the wild. It will quickly outgrow any balcony. Repot in the largest, practical container. Use a knife to cut vertically through the pot bound roots when repotting. Use minimal amounts of a slow-release, low-burn fertilizer. A weekly watering during the growing season should suffice. Ensure there is adequate drainage through the bottom of the container.

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