Answer: If you've check for obvious signs of insects and diseases but can find none, the problem is with the roots. Part of the root system is dying, either from old age, drought, overly wet soils or herbicide damage. If you've used a broadleaf herbicide under the dripline of the holly, the 2,4-D contained in most broadleaf weed killers can adversely affect the roots of your shrubs and trees. I can't diagnose the problem without seeing it but hope this information helps you determine just what might be going on with your holly.
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