Pear Leaves Turn Brown
Thank you for your question. It is difficult to diagnose a plant problem, especially susceptible species and gardening in the fungus capitol of the world! I was unable to find a disease (of a potential 30) with these leaf symptoms, but a person in Maryland was experiencing the same thing in 2016, and specialists there believed it to be caused by environmental factors: https://ask.extension.org/questions/199422 Do you water your trees? Here is an OSU Extension article on orchard care: https://catalog.extension.oregonstate.edu/ec819/html Good luck!
I suggest that you get a cheap water meter, and use it to measure soil moisture at least twice a week. I believe every 3 weeks is far too little, especially in this long weeks of no rain. Water deeply, until the meter indicates the water has penetrated to the root level (4-8 inches). Heat and no water can cause all types of abiotic (nothing living) problems.