Help! Pear tree leaves turning black

hyatan

My pear tree has been growing quite well despite the hot weather as I water it quite deeply.  However all of a sudden it has develop black leaves and increasing in numbers.  The pears seem unaffected at the moment.  I noticed only after it rained a couple of times but might be unrelated. How can I cure the tree?  Your sage advice would be much appreciated.

Pete.8

There was a similar post the other day 
I don't know that it is fireblight, but it may be

BobTheGardener

I think it's likely a combination of canker and the weather.  If you look at this close-up of the base of the twig which has the most obvious dead leaves on, you can see the canker has nearly completely encircled the base (centre of purple circle, below), cutting off the sap.  I would just cut it off below the damage then look for any similar areas and cut those back into healthy wood.

As the tree has lichen growing, it must be quite old and some canker is almost always present on old trees but can be controlled to some degree.

Fireblight may still be the culprit if it isn't canker I see.