Answer: Junipers are occasionally subject to a number of problems ranging from root rot, disease, or insect infestation. 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. Unfortunately, based
on your description it is impossible to make a diagnosis. You might want to contact your County Extension for a more specific identification of the problem and recommended controls. You can always prune out truly dead branches, but in this case the pattern may be a clue for diagnosing the problem so you might wait until you have done so with some certainty before you prune.
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