How annoying that this has happened to your blueberry bushes after they seemed to be doing so well. This is certainly bizarre and something I haven’t come across before but a bit of delving has come up with a couple of things that could be affecting your plants.
It is possible that the cold winter has had an effect – if you have had fluctuating spring temperatures in your area this can result in plants looking normal until temperatures rise in late spring. New growth and fruiting clusters suddenly collapse and die.
Alternatively it could also be some thing called Blueberry shock ilarvirus. The virus is dispersed by infected pollen carried by bees and infection occurs only during bloom. The symptoms are very similar to those of scorch being sudden complete flower and leaf necrosis (death!). A second flush of foliage occurs later in the season (without any fruit) so it may be possible that these plants will recover. I would move them somewhere out of the way and keep an eye on them rather than disposing of them straight away. If they show no signs of recovery remove and destroy the plants at the end of the summer.
Symptomless infected plants remain a source of infection so I would suggest keeping an eye on your other plants but as they are in a different location they may be ok.
Hope this helps.
Lynn Burton - Horticultural Adviser