Answer: Mandevilla likes heat and sun, it needs full direct sun all day and an evenly moist soil, meaning damp but not sopping wet or saturated. It needs a spot with good air circulation. It also needs regular fertilization during the summer with a water soluble fertilizer such as 10-10-10 and/or a slow release fertilizer. Read and follow the label instructions. Based on your description, I am not sure if your plant might have a fungal or bacterial infection, or if it is just in need of fertilizer. If you can adjust the growing conditions a bit, perhaps it will improve. If it continues to exhibit the same symptoms you might want to consult with your county extension. Good luck with your plant!
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