When black spots appear on the rose petals, gardeners should respond. In many cases, the well-known rose disease blackspot is the culprit. The stubborn fungus scarcely stops at any rose variety.

The disease blackspot

Black spot (Diplocarpon rosae) is a sac fungus also known as black spot. Many gardeners fear the stubborn disease that destroys rose petals. In most areas, blackspot overwinters on leaves that collect on the forest and garden floor. In the spring, blackspot infects the plants. Depending on the susceptibility, the fungal spores spread at different speeds. Various factors favor the spread:

  • wet weather
  • waterlogging in the soil
  • humus-poor location
  • clay soil

Varieties affected

Blackspot attacks various roses. Only a few varieties are resistant and protected from the fungal disease . The so-called shrub roses are particularly endangered. Preferably choose a hardy variety:

  • Angela
  • Dortmund
  • Yellow Dagmar
Note: Roses are not the only victims of blackspot. The fungal disease also attacks other plants such as oleander or laurel.


Diagnosing a disease of roses with the fungus blackspot is easy. Black fruit deposits form on the upper side of the leaves. These appear unevenly and contain fungal spores, which in turn aid in the spread. Diseased roses turn yellow in the spring and eventually fall off within a very short time. In summer, the diseased plants usually have no more rose petals.

Note: The black spots on the rose petals are typical of the disease. These are round, unevenly distributed, blurred and often spread out in a star shape. In addition, the leaves turn yellow.

course of the disease

Since the fungal spores overwinter on the winter soil, the disease usually starts on the lower rose petals. As the rainwater splashes on the leaves, the spores spread all over the plants. The roses lose more and more leaves, so that the energy metabolism slows down. As a result, the rose is further weakened and blackspot can spread. The diseased roses will not grow new flowers or shoots.

Note: The fungal disease usually begins in April or May. The speed of the course of the disease depends on the susceptibility of plants. Symptoms appear in the first two weeks after infestation.

Preventive action

Controlling blackspot is a challenge for gardeners. Consequently, you should take preventive measures to protect your roses:

  • pour
  • nutrient
  • location
  • maintenance

Waterlogging and splashing water favor the infestation of the roses. When watering, the water should not splash on the lower leaves.

Fertilizing the roses should be done without nitrogen. Potassium, on the other hand, can increase the resistance of roses to blackspot. At best, fertilize the roses in May.

Mushrooms prefer warm, humid areas. A sunny location is a good choice. Preferably, natural ventilation should dry the plants. Shady places are not welcome.

In the fall, you should remove any rose petals that are still attached to the plant. Removing the leaves from the plant and soil minimizes the chance that the blackspot will overwinter successfully.

take countermeasures

If you find rose petals with black spots, a quick response is required. Before the rose petals turn yellow, you should throw them away. Disinfecting the tool will prevent the fungus from spreading further.

Tip: The tool can be effectively disinfected with alcohol and a lighter. You can then continue gardening without hesitation.

Appropriate home remedies

Various home remedies are suitable for combating black spot and black spots on the leaves. You can use the following home remedies preventively and after an infestation. Be careful not to spray the roses in the sun:

  • horsetails
  • Knoblauch
  • nettle manure

You should plan a few days for the production of liquid manure. Place the nettles in a container with water and leave in the sun. Stir the nettle and water mixture daily. After the fermentation process is complete, you can use the dark liquid manure mixed with water in a 1:10 ratio.

Note: Repeat the process every week to combat blackspot effectively.

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