From the pic it looks like the yellowing is on one side of the plant? Looks like your using drip irrigation. Is the plant getting watered on that side? Blueberry plant roots feed the side of the plant that they are growing on. If thats the side the water is being delivered I would lean toward a ph issue. I would sprinkle alittle iron sulfate around the bush and see if it greens up for you. If so then a couple hand fulls of sulfer will do you all the good. The plant looks to be in good shape though. Just some minor adjustments should have you back in buisness. You are using well water right??? Could the plant be getting too much water??? Maybe the water ph is at fault???

I was thinking the same thing about possibly getting too much water.Is the soil fairly fast draining?The longer it takes to drain,the less it needs at each watering.Too much water can also wash out nutrients. Brady

The soil is very fast draining. I don't think it's a pH issue altho I don't know that for certain since my soil test was a random test for the entire group of plants. Too much water? That's possible.........thanks for the ideas. I hope it doesn't die, it's a good sized plant. To try and save it I cut back some of the top branches yesterday.