Thursday, February 14, 2008
Consider some factors before pruning damaged tree
John Arbogast
Landscape consultant John Arbogast answers your questions every Thursday. Send questions about your lawn, garden, plants, or insects to:
Dear John
5102 Greenfield St. SW
Roanoke, Va. 24018
Or send an e-mail. Answers will be given only in this column. Please don't send pictures or samples.
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Q: The recent very high winds snapped off a tall pine tree in our yard down to about 18 feet from the ground. We had the big fallen part cleaned up and will work on the part left standing in the spring. Can we prune that part and save it in our landscape? We live in Roanoke County.
A: Since I can’t see your pine, make your decision based on the following two important factors. First, think about a healthy tree’s ability to heal naturally based on the diameter of the wound. Pruning makes a wound, even if you follow pruning rules and make a smooth, fresh cut to the broken top of the tree just above a healthy side branch. By nature, trees try to “wall off” the cut area as defense against infection. However, most trees in the mid-Atlantic U.S.A. can only deal with 3-inch or smaller diameter wounds. If the diameter of the snapped top of the tree is larger than 3 inches, microorganisms might enter and kill the tree in the next few years.
The other factor is the amount of leaves, or needles in this case, remaining and their ability to make food for the tree. Trees can’t replace lost foliage immediately, and if any tree in this region suddenly loses more than a third of its leaves, that tree will starve in four or five years.
Q: Our maple tree, trimmed two years ago, has black bark at the base and also one large limb with papery white growth on it. Do these things mean that the maple is dying?
A: These things don’t mean that your maple is dying, but the black bark could be an indicator of trouble.
The black bark is likely the result of recent sap seepage or sap accumulation from drips or runs above the black area. This happens with various trees, especially maples, which are heavy bleeders of sap in mid-winter here in Roanoke.
Generally, sap loss is nothing to worry about. However, carefully examine the area of blackened bark for wounds or other bark openings from which sap could be flowing. Look for spots of decay and/or damaged bark that might lessen the maple’s structural strength.
Sap running from any plant should be allowed to flow, because attempts to block it might result in moisture buildup and rot.
The white, papery growth on that limb sounds like a harmless growth called lichen, if the papery part is dry. Take a sample of it to a plant expert to be sure.
Q: We hear a noise in our lower level between the paneling and the wall. My husband thinks that it comes from squirrels on the outside. We set traps inside the house in case of mice. What do you think this is and what can we do?
A: This could be squirrels, rats, mice, or possibly some other critters in the walls. I would suggest that you remove a small section of the wall where the sounds seem to be loudest and set a medium-sized box trap there, baited with some kind of nut product, to find out who the culprit is.
Set the trap more than once to be sure all the critters in the wall are gone, then look for all the ways the critters could have gotten into your walls, from the vents to the siding trim.
Have heavy-duty carpentry repairs made once you’re sure that all the current critters are evicted. Keep in mind that some wildlife can chew through wood, so all repairs must be strong.
