Bush Disease

[homedeeth]

I have an almost spherical bush/tree at the bottom of my garden. The half facing the house seems to be fine, the leaves are green, no holes in the leaves. The half facing away from the house seems to be disease ridden. Holes in the leaves, lots of brown leaves, lots of shrivelled leaves.
The back half does sit beneath the hanging branches of an oak tree which is in the neighbours garden.
Does anyone recognise this blight and what I can do?

[Chipchopper]

Probably not "disease ridden" but more likely affected be being partly under the canopy of the oak tree.
The bush may benefit by being moved away from the drip-line of the oak, if that's an option.