I agree with most of the above suggestions. However, I have read that pine needles don’t lower soil pH.
From Oregon State Extension:
" MYTH: Ponderosa pine needles make the soil more acidic (low pH).
REALITY: The notion that pine needle change the soil pH so that nothing will grow or that it will damage plants has been out there for years. The truth is pine needles do not make the soil more acidic. It is true that pine needles have a pH of 3.2 to 3.8 (neutral is 7.0) when they drop from a tree. If you were to take the freshly fallen needles (before the needles decompose) and turn them into the soil right away, you may see a slight drop in the soil pH, but the change would not be damaging to the plants."
From New Hampshire Extension:
" Pine needles themselves are acidic but do not have the capacity to appreciably lower the soil pH. To do that, it is necessary to incorporate a soil acidifier such as sulfur or aluminum sulfate. If you are unsure of the pH in your garden, you should have the soil tested. As pine needles break down and are incorporated into the soil, decomposing organisms gradually neutralize them. Thus, there is no harm in using pine needles to mulch shrub borders, flower beds and vegetable gardens. Even a 2 to 3 inch layer of pine mulch will not change the soil pH enough to measure."
I’m surprised that your soil pH is so high. Most soils in our area have a pH in the 5 range. Make sure you haven’t added anything to your soil that may have increased the pH. Do you know the history of the location the blueberries are planted? Maybe the soil was amended with lime in the past and the pH is still high.
With high pH soil blueberry leaves will appear light green with dark green veins. This is called iron chlorosis and is due to the plant’s inability to take up iron at the higher pH. The leaves on your plants look fine.
Also, rabbiteye blueberries are more tolerant of high pH, so I think you can still have success. I have read of others having good luck with rabbiteyes in neutral soil pH like yours.
If you had your soil tested by the NC Dept. of Ag. and let them know that you are growing blueberries, your report should have a suggestion on how to raise the soil pH. Here’s what my soil test report from 2018 said:
“It is difficult to lower soil pH to existing
blueberry plants; use of elemental sulfur (90% S) and ammonium fertilizer sources can be of benefit. Use proper safety handling instructions for use of elemental S; avoid breathing dust
and eye contact. Wash any S or fertilizer off plants to avoid burn. A rate of 5 lb per 1,000 sq ft of S will typically lower pH by 1 unit (6.0 to 5.0) for sandy soils; double the rate for clay soils.” I followed this advice, but haven’t retested the soil pH. I plan to this fall.
My suggestion is to play it safe and lower the soil pH. Apply sulfur at the rate suggested above or as in your report if different. Do this as soon as possible because it will take many months for the drop in pH. I would test your soil again in the spring to see where it’s at then. Soil tests are free in NC between April and November.
I would measure the pH of your water and adjust it down, if needed, as suggest by others. Be careful when using strong acids!
Rainwater has a pH in the 5 range, so you might consider setting up a rain-barrel to collect water for your blueberry plants if your supply water pH is high. I had success with this when I lived in Illinois.
Use ammonium fertilizer as suggest in the soil test report and by others above.
I wouldn’t let the plants produce fruit next year. Let them put energy into growth. I have experimented with this in the past and have confirmed that the plants will grow much faster if not allowed to fruit when small. My experience has been that the plants put growth on hold when developing fruit and then return to growing again after harvest.
It has been several weeks since you first posted this topic. How are the plants doing now?