One of the leaves in the first shot has been tunneled by a leaf miner. The rest of the leaves are currently or have been recently heavily infested by something like mites - look at them with a magnifier to see if anyone is still in residence. If so, you will have to identify them in order to follow up with an effectively targeted control regimen.

Thanks. Yes, the leaf miners have been around for a while and hard to get rid of, but with some pruning this has been minor cosmetics. This 'browning' of the leaves is new and looks more damaging. I will see if I can get a close up photo of any creatures under the leaves.

Looks fungal to me. You could try a fungicide and avoid watering late in the day.

Jane

There's stuff visible that looks like insect debris (in which case of course it's probably not mites).

Reminds me of spider mite damage - or something similar...