Do you know anything about tree diseases?

We have a pear tree in our back yard. It is approximately 10 years old and I do know it should live much longer than that. Unfortunately, many of the leaves started turning brown and then rapidly crunchy as did the limb, very soon the entire limb died. Its spreading over the whole tree now, but it is trying to put out new leaves and branches, they too are getting consumed by this mystery illness.

About 50 feet away we had a bush that put out lovely yellow flowers (sorry, don't know what kind it was). This bush was about 8 years old and kept trimmed over the years at about 4 feet tall. Not long after the pear tree started turning this bush did as well. Turned completely brown and 'crunchy'. I was just pulling on the top of one of the dead looking branches and the whole darned bush pulled right up out of the ground. It weighed nearly nothing and was completely dehydrated, even the dead parts were dead! Never had anything like that happen.

Anyone have any ideas on what may be going on here?