To control black spot on roses, remove the affected leaves and canes and spray the plant with fungicidal spray. If the problem persists, move the rose plant to a different part of the garden.Continue Reading
Black spot is a plant disease that causes black spots on the leaves of rose plants. It is caused by a fungus called Diplocarpon rosae. The disease can weaken plants and cause them to succumb to winterdamage. Gardeners can control black spot using the following steps.
Remove leaves that show signs of black spot. If several parts of the plant are affected, prune back canes infected with the disease.
A fungicidal spray can help manage spores and keep the disease from spreading and infectingnew leaves. Apply and reapply the product as directed on the label. Continue to remove affected leaves, as fungicidal sprays cannot cure leaves infected withblack spot.
Like many fungi, black spot thrives in damp environments. Therefore, keeping the leaves dry can stop the fungus from spreading. Water the rose plant at the bottom and avoid using sprinklers or other overhead watering systems.
Air circulation helps dry moisture away from the leaves. Therefore, pruning the rose bush to let air circulate helps manage black spot.
If pruning and spraying do not control the black spot, try moving the plant to a different location. Move it somewhere where it can get more air circulation. Sunny locations that leave some distance between other plants and away from fences are ideal.