Reasons for Blueberry Chlorosis
What causes blueberry chlorosis? Most often, chlorosis in blueberry plants isn’t caused by a lack of iron in the soil, but because the iron isn’t available to the plant because the pH level is too high. In other words, the soil is too alkaline for healthy growth of blueberries. Alkaline soil is often present in areas where rainfall is low. Blueberries require a low soil pH, and chlorosis occurs when a high pH level binds up the iron in the soil. Although the optimum pH level may vary somewhat between different cultivars, a pH above 5.5 is often cause for chlorosis in blueberry plants.
Blueberry Chlorosis Treatment
The first step in blueberry chlorosis treatment is a soil pH test. Your local cooperative extension office may provide tests, or you can purchase a testing kit relatively inexpensively at a garden center. If leaves are looking puny, a foliar iron spray is a temporary fix that will get the plant through a rough patch while you are figuring out the next steps. Be sure the spray is marked “chelated” iron. Reapply the spray as new leaves appear. A longer-term solution involves application of sulfur to lower soil pH, and this is where things can get complicated. For example, method and rate of application will vary considerably if your soil is loam, sand, or clay. There are a number of products on the market, including powdered sulfur, pelleted sulfur, elemental sulfur, lime sulfur, aluminum sulfate and others. The best sulfur for blueberry chlorosis treatment depends on soil pH, soil type, moisture, timing and other factors. Your cooperative extension office will have plenty of fact sheets and other free information about blueberry chlorosis treatment in your area. In the meantime, there are other steps you can take to improve the situation for your blueberry bushes. However, none should be considered substitutes for correction with sulfur products.
Water regularly, especially during dry periods. Mulch well with bark chips, pine needles, oak leaves, or other acidic materials. Fertilize regularly using a high-acid fertilizer.
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