Either the soil is too dry or too wet, or you are seeing the combination of stresses and some mites or disease problems accumulating over the long hot summer. You can cut them back at the end of winter and if you like at the end of summer to force new growth and a nice fresh appearance. It is borderline now as to whether you should cut them back or not. But if they are really too ugly I'd cut them back even this late. Just be aware that winter will do some damage to the new growth and another late winter cut back will be needed.
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