My tree is in terrible shape. The leaves have what looks like a lot of black mold on them. One side of the tree has lost all of its leaves. My landscaper planted this tree last year and I'm wondering if the sprinkler is watering it too much. This tree looks like it could die.
Your intuition is correct on two points: it is indeed a type of mold, and it is indeed getting too much water. Your Japanese blueberry has sooty mold, but that's not the real problem. Sooty mold only grows on honeydew, which is a polite term for what comes out of the back-end of an aphid, scale, or other sucking insect. (It is high in sugar: hence the name.) So if you get rid of the scale, then you remove the food source that the sooty mold grows on. Simple, right? Well, not always. Some scale insects are really difficult to control. There are organic solutions, and there are some that are derived from compounds found in nature but are actually synthesized in a lab. These work pretty well. You will not likely get control of scale on Japanese blueberry with something purchased over the counter. I espouse a nutritional/cultural approach. Cut off their irrigation almost completely, and incorporate organic matter into the soil (you can hire us to do this by our Root Invigoration procedure). Poor soil nutrition and wet feet make Japanese blueberry more susceptible to scale and other sucking insects. Mulching, root invigoration, taking steps to improve internal drainage--all these things can help, but you need these guys gone now! You could wipe each leaf clean, but it would be labor-intensive and the results would be disappointing. Horticultural oil helps, but you're too late to apply the more effective winter rate. If these corrections don't result in an improvement by early summer, then you might consider a systemic treatment. We'll be happy to provide you a quote to help take care of the problem. Chances are, it's not the only plant getting too much water.
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