alder leaf disease

We have a hedge of about 30 alders which were cut with an electric hedge-cutter about a month ago. Noticed, a week or so ago, that many of the leaves are curling and have, mostly either side of the spine, rows of 'pimples', each 3-5 mm in diameter. They seem to start being pale green with small brown spots, then the middle of each spot cracks into a hole. 

Will be grateful for diagnosis & treatment.

gillylal, any chance of a pic? It sounds to me like scorch, where droplets of water has splashed on them, which then acts like a magnifying glass, scorching the leaf.

Thanks for replying. New to this forum and can't see how to post a picture....?

Haven`t been here long myself.lol If the spots go brown and papery before cracking, then 9 times out of ten, that is scorch, Nothing to worry about.

Is that gall mite?

Looks like it - thank you. See: http://www.aphotofauna.com/mite_gall_eriophyes_laevis_alder_leaf.html

Seems like it is gall mite, which can affect alders - but I can't find any hints on the net as to how to treat this - or whether or not treatment is necessary. Please can anyone suggest anything?

I don't think any treatment is either necessary or possible. Normally healthy trees don't have a problem with galls. I'll rephrase that - they won't suffer ill effects!

Many thanks - reassuring.