Answer: A fungus causes black spot on roses. Some cultural practices may be helpful in controlling it. These include planting varieties resistant to it, ensuring your plants are in a location with good air circulation, avoiding wetting the leaves when watering, and cleaning up, removing and destroying any infected leaves. Do this especially well each fall to minimize reinfection from year to year. A clean layer of organic mulch (such as shredded bark or half finished compost or chopped leaves) applied before the plants leaf out again in spring should also help prevent reinfection. Ortho's Rose Defense will help control black spot.
Japanese Beetles can be hand-picked or you can use a rose systemic to combat the pests.
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