Black spot is a disease that occurs in roses and happens as a result of a fungus known as Diplocarpon rosae which infects the leaves and has an effect on the growth and health of the rose plant. There are a number of ways in which you can control the spread of the fungus and this includes removing any infected leaves that have fallen on the ground as well as pruning back any diseases areas of the rose. You can also find Black Spot On Roses Remedy that will help to control the symptoms.
Here are some of the symptoms that you may notice on your rose plant. Equally in some cases the only evidence that you will have on an infected plant is the leaves dropping from the rose from Spring time onwards.
Usually, on the upper leaf surface, a rapidly enlarging purple or black patch emerges, with the fungus’s diffuse and radiating strands only visible.
Leaf tissues around the spots will turn yellow and the leaf sometimes drops to the ground, while other sections are still unaffected. In some cases the yellow colour does not occur but the infected leaves still drop. This is why it is important to ensure that you remove any leaves that drop around an infected rose to help stop the spread of the fungus.
On young stems, thin, black, scabby lesions can also appear as well as smaller black spots that may be difficult to see unless you carefully inspect the stems.