Hedge Dieback

This problem is occurring in a couple of areas where buds are either deformed/stunted and fail to open or open to reveal fragmented leaf shape (sometimes holed) and of a clearly lighter colour.  This is extended down a couple of hedging plants with some dieback of branches. There is no sign of a fungal root problem or bark lesions but affected leaves are sticky in some cases. The hedge runs alongside a tall wooden fence and there are shrubs/trees in close vicinity. Any ideas would be appreciated.