These are blueberry plants that I put in this spring. The plant on the bottom is healthy. The one on the top has interveinal chlorosis, which shows iron deficiency. Note the yellow between the green veins, on the new shoot. The soil here has come from basalt rock. This rock is 17% iron! But it doesn't get into my plants, because the ground is not acid enough. I put aluminum sulfate on the ground to make it more acid. Some of the plants have already greened up. I expect this one will, as well.