Blueberry leaves drying
There is a lot going on here in that it is hard to rule things out. Watering a lot. Blueberry is a shallow rooted plant and needs less water more often (as opposed to more water less often). It also needs low soil pH so we need to know if it is in the 4.5 to 5.5 range:
That is step one.
Step 2: It looks like the root crown is buried under a lot of saw dust. If that is too deep then maybe the plants are rooting into that upper zone and then drying out too fast. You might expose that lower area to the air.
3 - do you have a heavy clay soil? You might be watering too much and encouraging a root rot. See here:
4 - after that I am still not able to rule out a wide variety of shoot diebacks such as twig blight:
See if any of these things apply to your situation. That is about all I can come up with based on your limited information and image. Good luck.