I have a Bradford Pear tree in my yard that the leaves are turning brown throughout the tree. I've check for insects or worms and have not seen any. I hope the pic's will help.
Those brown stems and leaves are certainly indicative of Fire Blight, a dreaded bacterial infection of many members of the Rosaceae family (to which your Pyrus calleryana 'Bradford' belongs). Though not rampant among Bradfords, these fast growing, short lived trees are certainly not entirely resistant to this disease.
I agree. Fireblight is a fairly aggressive disease and without prompt treatment, can cause death of the tree. You still have a lot of green foliage so hopefully the infection hasn't spread too far. You will want to prune off all of the infected stems. Make your pruning cuts above where there is a healthy lateral branch but well below any dead tissue. I have heard recommendations of 1-2 feet into healthy tissue to make sure you've got it all. Sometimes you have to cut the branch where it attaches to the trunk.
When you do this, make sure you have rubbing alcohol or 10% bleach solution and sterilize your pruners between EVERY CUT!
Keep an eye on your tree for new infections and be diligent about removing them as soon as they appear.
