Hi Alex and welcome to garden.org Your blueberries are probably suffering from iron chlorosis. This may be due to the roots reaching out to some soil that is too high in pH for them. If you go to your local nursery (a real nursery, not a big box store) you can ask for a chelated iron product that will help correct the pale color on the plants for this year. Ammonium sulphate fertilizer will also help but only very temporarily and you really don't want your bushes putting on a whole lot of new growth this late in the season, unless you live in the deep South? (you could fill in your profile to include your location, and then it will appear in your posts)
But extensive amendment of the soil all around the blueberries extending out well past the reach of the branches is needed to keep soil pH from rising too high for these little acid lovers. Mulch the bushes each fall with a deep mulch of leaves, and then top dress each spring with a combination of compost and peat moss. Not just a shovel-full per bush, more like a whole wheelbarrow per bush will be needed this next year. Then keep up that good work to keep your blueberries healthy and productive. It's hard work to keep soil acidic enough for blueberries if your native soil is not acidic. The pH always tends to rise again.
I'm in the same boat here, planted blueberries in a big, raised bed that I thought I could keep acidified enough, but still . . those roots keep growing and the leaves are like litmus paper, indicating by their color that they're getting out into the alkaline soil.
