Selfsufficientish.com

Hi, I have some apple trees I planted about 13 years ago. Two of them Topaz and Winston have never really produced fruit of any great size, even if I thin them out they don't seem to do much. The Scotch Bridget was pretty good, but in the last couple of years, these three trees have been getting these brown leaves, the Discovery seems to be ok. I am now thinking do I have fire blight, fruit trees are a new thing for me as I never had space before and all the apple trees I have ever had any dealings with have been old and still producing fruit with no care.