HelpfulGardener.com

Hi,
Could you, please, help me identifying the disease on a pear tree (reddish spots on young leaves - see picture below)?

This looks like Pear Blister mite Algida.
It's a minute mite that lives under the skins outer layer, causing the blisters you see. Later in the year they will turn black in colour.
The mite is relatively harmless to the tree though, and providing they are not too numerous they will not effect the cropping of your tree.
At present there is no effective control ...either chemical or biological for the gardener.
The mite overwinters in the dormant scales that wrap the sleeping buds on the tree so other than clearing fallen leaves and burning them, there is nothing else to do I'm afraid.

Thank you very much.