Answer: Blueberries require special soil conditions to grow and fruit well. If these conditions are not met, they will not thrive. It sounds like your soil may be too dry, or it may not be acidic enough, or it may not be humusy enough, or it may not be well enough drained, or you may have overfertilized -- browning and yellowing can be caused by many different factors and it is very difficult to make a diagnosis long distance. Here is some general information about growing blueberries to help you review your growing conditions and see if they are suitable. It was written for Ohio but is equally applicable to your area.
Your local county extension may be able to help with soil tests and interpreting the results, and with troubleshooting as well. I hope this helps.
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