what's a matter with my pear tree? please help

Hi 

i could do with some really good advice. Am totally novice and back in March bought two apple and pear trees. The conference pear tree is not thriving and looks unwell; i need to know what's causing it and how to treat, also do not want possibility of spreading to other trees.

Symptoms; new shoots are shrivelled, with some blackening to edges. existing leaves have brown/black blotches which seem to spread across leaves, leaves then become torn and/or have found several black/brown leaves on ground. Leaves are not sticky. Branches seem healthy.

Try searching Google Images for "pear blister mite" and see if the images match your leaves.

thank you will take a look at this

Had a look but don't think it's this - any other ideas? could it be scab?