A common rose disease is black spot on roses. Here are some rose bush care tips.
This extremely common fungal disease, 'Black Spot' infects rose foliage, causing circular black spots with fringed margarins. This rose disease is actually a fungus ( Diplocarpon rosae) and is a severe problem where there is high humidity or lots of rain.
The fungus lives through the winter on infected leaves and canes. The spores are spread from plant to plant from splashing water and rain. The fungus enters the tissues of the plant, and forms tiny pinhead size spots. The black spots on roses enlarge as the fungus spreads, to the point that, spots may join to form blotches.
Black spot spreads quickly when the weather is wet or humid and warm. When this disease of roses,severely infects the plant, the foliage turns yellow and drops off prematurely. If left unattended, plants may lose all of their leaves by midsummer.
Plants infected with this disease, lose vigor, and flowering is greatly reduced. The plants become ragged looking, without their foliage. For this disease to take hold, the fungal spores must stay wet for around seven hours. Wet foliage overnight, or a rainy day, readily allows the infection to start.
Black spot on roses is most severe in regions with higher
rainfall, including the Southeast, Northwest, and the East, but it can
occur anywhere, in any area.
The first and easiest way to avoid this rose disease, is to purchase roses that are immune to it. Many varieties have very good resistance to it. (Check the label when you buy your rose)and buy it from a reputable company.
If you already have plants in the garden:
Avoid watering from above. Spraying the leaves with water from above, only encourages the spores to take hold.
Rake and destroy fallen leaves in the fall (Do Not Compost them)
Space plants to ensure good airflow and drying after the rain.
Prune the plants to 'open them up' and allow good air circulation.
Water in the morning to minimize the time that the plants stay wet.
At the first sign of disease,remove infected
leaves (do not compost) and begin spraying with an organic solution.
This spray for Powdery Mildew is also effective on Black Spot. Read how to make this simple recipe yourself here.