Answer: A fungus causes black spot on roses. Some cultural practices may be helpful in controlling it. These include planting varieties resistant to the disease, ensuring your plants are in a location with good air circulation, and avoiding wetting the leaves when watering. Clean up and destroy any infected leaves, especially in the fall to minimize reinfection from year to year. A clean layer of organic mulch (such as shredded bark or chopped leaves) applied before the plants leaf out again in spring should also help prevent reinfection. The mulch helps keep fungal spores from splashing up onto the plant and the new foliage. Neem oil may also be helpful. Neem controls aphids and mites on your roses, and also will control powdery mildew and black spot. Be sure to read and follow the label instructions. There are also other commercial fungicides available. Best wishes with your roses.
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