Q: I have six blueberry plants. Two of them have very yellow new leaves and the other plants don’t look so great either. I know this indicates a problem with the pH. In late May I fertilized them with azalea fertilizer hoping this would make the soil more acidic. I sprayed with Schultz Iron Green to help them green up. They still look pretty sickly.
A: Chlorosis (yellowing) of blueberry leaves is partially caused by soil acidity higher than blueberries prefer and partially by a heavy fruit set . Lawns need lime to keep the pH above 6.0, but blueberries like a pH level between 4.0 and 5.3.
Have your soil pH tested by the Extension service (404-897-6261). Only in that way will you know whether you need to apply sulfur to lower the pH any further. Spraying with a chelated iron product like Ironite or Iron Green is a good temporary fix. It gives iron to the blueberries through their leaves rather than their roots.
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