Answer: The cause for the black rot can be the fungus Phytophtora omnivora. It is possible that you used infected scissors when you were cutting off the blossoms and the disease has spread to your plants. The other cause for the black rot can be the soil isn't porous enough and holds too much water. When watering the plant you have to be careful not to wet the leaves; it's better to water the plant in the morning so the foliage will be absolutely dry throughout the night. After cutting off the blooms and old leaves, it is important to let the wounds dry before watering your plant. Although you can try to save your plant with fungicide applications, I think the smartest thing you can do right now is to throw away the plant. The
fungicide treatment can be quite expensive and the value of the plant is relatively small. Best wishes with your garden!
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