Black Spot

Black spot is one of the most common and important diseases of roses throughout the world. It is caused by the fungus Diplocarpon rosae, which can cause the following symptoms:

• A general weakening of the plant so that progressively fewer blooms are formed if the disease is left unchecked
• Black spots, especially on the upper leaf surface, ½ inch in diameter with fringed borders and tiny black spore-producing bodies (upon close inspection)
• Yellowing of the leaf areas around the spots
• Entire leaf may yellow and eventually drop off
• Black or purple lesions on the canes