Not much hope of helping you based on that information. Could you post a picture? More information? Potted or inground, pH, watering schedule, etc???

It helps to know what state you are located in, and also, when the blueberry shrub was planted. Do you have soil that is high in clay content? If the shrub was planted this past spring, and, if the native soil is high in clay, then it could be that the roots have not developed fast enough to support the metabolism that is happening in the leaves, during high summer. One way to support the plant is to provide partial shade from the summer sun. My experience with blueberry shrubs has been that it can take 6 months for a transplant shrub to develop a good root system, in the new location.