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Ask the ISU Extension Experts

Note to media editors: Got gardening questions? Contact the Iowa State University Extension Hortline at (515) 294-3108 (Monday-Friday; 10 a.m.-12 noon and 1-4:30 p.m.) or send an e-mail to hortline@iastate.edu. For more gardening information visit us at Yard and Garden Online at www.yardandgarden.extension.iastate.edu.

10/3/2007

The bark on a tree is cracking and peeling off.  Is the tree dying? 
Peeling bark on trees may be completely harmless or indicate a serious problem. The bark on most young trees is smooth and thin.  As the tree grows, the bark layer thickens with the outermost tissue eventually dying. Continued growth of the tree pushes the bark outward, often causing the outer layers to crack.  On some trees, the outer bark layers peel and drop off, revealing inner layers of bark. The inner layers are usually smoother and colored differently than the outer bark.  Shedding or peeling bark is a characteristic of trees such as the shagbark hickory, sycamore, birch and redbud. Peeling bark on these trees is normal and no cause for alarm. 

Trees definitely have a  problem if the bark is coming off down to the wood. The tree should survive if only a small portion of the bark is lost on a tree’s trunk. However, the tree may eventually die if additional bark continues to fall off the trunk. Unfortunately, little can be done to help trees that are losing bark. Any loose bark can be carefully removed. Applying a pruning paint to exposed wood is not beneficial. 

I’m planting a large balled and burlapped tree that has a wire basket around the rootball.  Do I need to remove the burlap and wire basket when I plant the tree? 
After digging an appropriately-sized hole for the tree, carefully lower the tree into the hole. Then begin to backfill with the original soil. When the planting hole is one-half full, cut and remove all twine. Also, cut away and remove the burlap and wire basket on the top one-third to one-half of the rootball. Then fill the remainder of the hole with soil. 

How do I overwinter a mandevilla? 
The mandevilla is a twining, tropical plant. In Iowa, the plant should be brought inside in September before the first frost or freeze. Indoors, a brightly lit location (for example, an east window) is ideal for the plant. The low humidity levels in most homes during the winter months can be a problem for the mandevilla. 

The humidity level around the plant can be raised by placing it on a saucer or tray partially filled with pea gravel and water. The water level in the saucer or tray should remain below the top of the gravel so the pot is not sitting in water. The water evaporating from the tray will raise the relative humidity around the plant. Water the mandevilla when the soil surface becomes dry to the touch. Typical room temperatures are fine. The plant can be pruned back periodically if it is getting too large. Next spring, the mandevilla can be brought back outdoors in late May or early June. 

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Contacts :

Richard Jauron, Horticulture, (515) 294-1871, rjauron@iastate.edu

Jean McGuire, Extension Communications and Marketing, (515) 294-7033, jmcguire@iastate.edu