Have you always used pots or have you planted any directly in the ground?

Possibly stem blight. Some varieties are more resistant. I've lost a few.

I have always used pots, for two reasons. One is that my soil is alkaline, and the other is because trees that are planted in the ground belong to the property owner (and transfer when the house is sold), but potted plants remain the property of the tenant. So, if I sell my house, I can take my blueberry plants with me.

You can move in-ground plants before you move/sell, assuming it is written into the the sale of the land/house.

I struggled with potted plants due to water. mostly too much of it drowning parts of the roots. there is a container gardening section here.

Also there is the dude that does cloth bags inside his pots and waters with rain gutters. Just Google that, you'll turn it up. His method is pretty impressive