Answer: The dieback you describe could have many causes - some kind of injury to the root system, fungal disease, insect pest, etc. Look closely for insect eggs, droppings, evidence of chewing or boring, or for signs of fungal infestation such as cankers or blisters on the bark. These will help you narrow down the possiblities. Contact your county extension office (414-335-4709) with your findings, and ask for an ornamentals or landscape specialist. They will be able to make a recommendation based on what you've found.
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