Check the soil pH every year or two, especially if plant growth is poor. Iron deficiency is common when the soil pH is too high. Normally, young leaves are a lighter green than older leaves and often have a slight reddish tint. When deficient in iron, young leaves become pale yellow and stunted, and plant growth is poor. If iron deficiency occurs, make every effort to correct the soil pH. Water or lightly rake sulphur into the soil or mulch according to the pH. To avoid possible burning of the blueberry roots, delay the sulphur application until one month after applying the fertilizer. Foliar sprays of iron chelate can temporarily correct an iron deficiency. but annual sprays may be necessary. 谢谢