Answer: Most roses can recover and releaf if they are otherwise healthy. Mid August is not a good time to prune because the new growth will be very tender and likely to winterkill as a result. Black spot is a fungal infection and can be difficult to control. Using an appropriate fungicide according to the label instructions along with removing any infected leaves and a very thorough clean up of the area around the plant can help. It is also good to keep the plant pruned regularly to enhanc eair circulation through it and to avoid overhead watering. Using a fresh layer of new mulch each spring can also help reduce the reinfection rate. In the end though, some rose varieties are more prone to black spot than others so if you have one that is particularly susceptible to it you might consider another variety.
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