Several possibilities.

Need pictures, please

jean001a, thank you for advising. Raining here all day, but will get some pics tomorrow if rain lets up. :)

jean001a, here is a picture of the Asian pear tree where the leaves are turning brown. Can you tell me what is causing this, from looking at the picture? Thank you for your help and any help from anyone else on this matter. I really don't want to lose my pears.

It's hard to tell by the picture, but more than likely it's
fire blight. You need to prune out those branches ASAP.

Not sure what it is, either. It could be some type of fire blight, a common and serious disease on pear (and apple)

I attached the fact sheet of fire blight for you.

Here is a link that might be useful: Fire blight fact sheet.

Thank you so much for all of your help. rayrose, I am going out to prune out those branches, as soon as it stops raining. And, mamuang, thank you so much for the Fire blight fact sheet. It is very helpful. I am going to get them sprayed ASAP, right after I prune those infected branches. Hopefully, I can save my pear tree and my pears.

I wouldn't spray, unless it gets out of hand. Pruning and a daily inspection for new strikes should do the trick.