black spots on roses - Knowledgebase Question

buffalo, Ne
Question by flbh
July 16, 2009
minature roses leaves have black spots, one bush no leaves. how can I prevent destruction to other rose bushes?


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Answer from NGA
July 16, 2009

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The symptoms of black spot begin with circular black spots, frequently with fringed margins. Yellowing and defoliation are common in susceptible cultivars. In wet weather, spots may become very severe and run together, making large irregular spots. Control practices include avoiding dense plantings (good air circulation all around the plant is important). Avoid overhead watering. Rake up and remove all leaves at the end of the season. You can try removing the yellowing leaves as soon as you notice them, but I suspect the canes might also be infected. A copper-based fungicide should stop the disease in its tracks. If you use a preventative spray in May and June, your rose should not develop black spot in July. Try putting your rose on a regularly scheduled spray schedule. Or, use a product like Rose Defense which has some residual action. Best wishes with your roses.

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