I have a few blueberry plants that this spring seem to be very off color. I think the ph is to high in the soil. I applied garden sulfur around them this spring and I have been irrigating them with 21-7-7 acid fertilizer and another chemical to reduce ph in the soil. I am having no luck getting them to green up. I was going to put more sulfur around them but I don't want to hurt them either by putting too much around them. Anyone have any other suggestions that I should try?