Diplocarpon rosae

Black spot on a rose

Blackspot ( Diplocarpon rosae ), also known as black spot, is an ascomycete that causes one of the most common fungal diseases of the rose, but other plants, for example, affects the bay.

The leaves show first round, black and brown spots, often spread out in a star shape. The affected leaves turn yellow and eventually fall off. Thereby the assimilation is limited, which means a weakening of the plant. Leafless plants bring little new produce flowers, new shoots can form no wood and can not mature, resulting in a reduced frost hardiness result.

The disease is caused by over-wintering in the soil fungal spores which are often sprayed by incident cast or rain water on the rose, where they spread more or less depending on the sensitivity of the variety.

To prevent a disease, it is important by selecting the appropriate nutrients to increase the resistance of the plant. Since the infestation is difficult to control, it is recommended that the plants are sprayed preventively, starting in May. When watering, make sure that is poured only to the root in order to provide the fungus not a humid climate on the leaves.

If the plant is ill, they must be treated with a suitable spray. Sick leaves and infested shoots should be removed and disposed of in the trash can to prevent the spread of infection.

In addition to the use of plant protection products and the spraying of roses with horsetail is recommended. Beginning in the spring, you should water the roses regularly with ausgegorener nettle liquid manure and sprinkle the soil with wood ash beech.