The Q&A Archives: Cure for virus?

Question: I have a rose, my favorite plant, that I have been told has a virus. It will grow leaves and flowers well, but occasionally on established growth, the leaves will be spotted with yellow, then dry up and die. Is there any treatment so I can save it? Thank you.

Answer: I'm not sure your rose has a virus. Virus on roses shows up in distinct patterns on the leaves, not yellow spots. To be sure, take a few of the leaves into a local Master Gardener Clinic or ASU Extension office. A more common problem is black spot. 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 be helpful. It is sold as Ortho's Rose Defense. 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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