Pear tree blister mite problem

I have the same thing mbirtles.

RHS advice is here: https://www.rhs.org.uk/advice/profile?pid=661

It says you can remove the leaves now if it's not a heavy infestation, in which case it will do more harm than good.

My dwarf pears have been infested with this pest for the last 2 years. I decided to research it and found that there is not much info available to UK gardeners on how to deal with it, especially since the EU banned previous chemical solutions. The best cure involves using horticultural oil diluted in water, this must be applied by spraying every single bud before they start opening in late Winter/early Spring. What the oil solution does apparently, is suffocate the microscopic mites that live in the buds. If left too late, spraying is ineffective as the mites burrow into the leaves. I sprayed mine in March and have no sign whatsoever on any mite infestation on my trees so far! Very impressed 

If you can't get hold of horticultural oil, the following recipes work apparently:

4.5 litres water + 3 tablespoons good canola or veg oil + 1 tablespoon bicarbonate of soda

or, 1 gallon water + 1 cup veg or soybean oil + 2 tablespoons liquid dish soap

or, Vitax 2 in 1 Pest & Disease Control spray.

As it's too late to spray this year, apparently picking off all affected leaves works well, the trees soon recover. Good luck, hope you get rid of the mite.