is it a disease - Knowledgebase Question

Washington, Di
Question by poohpratt1
September 28, 2009
The leaves on my 2 yellow and 1 white rose bushes have developed (1st black then yellow) spots on their leaves. I have cut the bushes all the way down each year thinking this might remedy the problem. No luck

Answer from NGA
September 28, 2009


What you describe sounds like a disease called black spot, which is common on roses. 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 roses should not develop black spot later in the season. Or, try a neem oil product such as Rose Defense on a regular spray schedule (as recommended on the label) to keep your roses black spot free. Best wishes with your roses

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