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Copper beech tree bark problems

Updated November 21, 2016

The copper beech tree also is known as the European beech and the purple beech. It is commonly used in North America as a large-scale landscape tree. It grows 70 to 80 feet tall and has a large spread of 50 to 70 feet. Some cultivars have a weeping look and their branches trail on the ground. The copper beech is susceptible to the same deadly disease as other beeches--beech bark disease resulting from woolly beech scale. It is more common for older trees to succumb to disease than young ones.

Healthy Bark

Healthy beech tree bark is greyish silver in colour and relatively smooth to the touch. In the spring and summer, its pale colour contrasts beautifully with the purple leaves of the European beech.

Scale

Scale insects infest trees and garden and houseplants alike. Due to the waxy substance they excrete, they also are associated with fungi that can do significant damage to the plant in question. Beech trees are susceptible to infestation by Cryptococcus fagisuga (C. Fagisuga). The U.S. Forest Service describes the insects as yellow and elliptical in shape and about 0.5 to 1.0 millimetres long. Scale insects excrete what is described as a "woollike," white, waxy substance. Eggs are laid in midsummer and they hatch in late summer through early winter. Nymphs force their tubular styles into the bark to feed on its liquids. These holes allow the Nectria fungus to enter the bark, which is far more destructive than the scale, although the scale weakens the tree's natural defences.

Beech Bark Disease

European beech is susceptible to infection by Nectria coccinata. The Nectria fungus releases spores into the bark, which feed on it and cause cankers to form. These cankers may eventually girdle the tree, at which point twigs and branches begin to die, and the bole (trunk) is also susceptible to breakage. The fungus has an asexual and a sexual stage, each looking distinctly different. During the sexual stage, the fungus puts out bright red fruiting bodies. These bodies are filled with sacs, each of which contains eight spores. The sacs mature in the fall and release their spores when they are moist. The asexual stage looks white and almost flaky; it may be mistaken for scale insects. Spores are released midsummer until the fall and are easily spread by the wind.

Look for red-brown dead spots called "tarry spots." These are the first symptoms of Nectria infection.

Other Insects and Diseases

Scale insects open the door for other destructive organisms to enter the wood. Hypoxylon bacteria enter the sapwood beneath the dead bark and are among the first to invade infested trees. Ambrosia beetles and shoestring rot fungus are other problems. Xylococculus betulae create defects on young beech tree stems, and weakened, roughened bark is easily infested by beech scale, then infected with Nectria; infected trees will not reach maturity.

Treatment

Remove scale insects as soon as possible by spraying them with water from a hose. Depending on the size of the tree, this may be possible to do yourself. Monitor the tree until you no longer see any scale insects. Ladybirds and nematodes are beneficial insects that feed heavily on scale insects. If these measures are ineffective, an insecticide should be used. Your local County Extension Office is a wealth of information regarding tree diseases and treatments.

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About the Author

Based in Fort Collins, Colo., Dannah Swift has been writing since 2009. She writes about green living, careers and the home garden. Her writing has appeared on various websites. She holds a Master of Arts in English literature from the University of New Hampshire and is currently pursuing a certificate in paralegal studies.