Anyone identify what's wrong with my rhododendron ?

[roosky]

Can anyone identify what's wrong with this rhododendron leaf ? Several of my plants have this problem. The leaf seems rather dry, as well as discoloured.

[Scarlet]

Have you had it for a long time? Are you growing it in a pot or in the ground?
Rhododendrons need acidic soil to grow well and don't like being watered with tap water.
Have you fed it recently?

[mothhawk]

Have you looked on the underside of the leaves? Could be a sap sucking insect like a lacebug

Pieris lacebug/RHS Gardening

[shushkin!]

Have you looked on the underside of the leaves? Could be a sap sucking insect like a lacebug

Pieris lacebug/RHS Gardening

Yep, my moneys on some sort of sap sucking insect to.

[roosky]

Thanks for your replies, everyone. The concentration of the discolouration along the veins, rather than all over the leaf, makes me think it's not a lacebug, However, although it's in the ground, it hasn't been fed, and in dry spells it's been watered with tap water, so maybe altering the last 2 variables might help !