Black star soot is a serious fungal infection that occurs primarily on roses, but can also affect other plants. The infection can cause the plants to become bald, weakened, and eventually die. Since the spores of the fungus spread quickly and are resilient, treatment requires a lot of patience and a thorough approach.


As the name suggests, the soot rope has an irregular shape that is roughly reminiscent of a star. The spots on the leaves and bark of the affected roses may be sooty black. But also be brown or purple.
Typical signs of infection with the fungus include:

  • Yellow discoloration of the leaves
  • Leaf loss up to balding
  • young shoots no longer develop lignified bark
  • Plants show irregular brown, purple, or black spots
  • the plants are weakened and less resistant to frost

Risk factors

Like many other fungi, star soot mainly spreads in damp environments. Watering from above, during which the leaves are wetted, or watering in the evening – after which the leaves can no longer dry off – are therefore possible risk factors. But also:

  • Too little spacing between the plants, which prevents rapid drying
  • high dew
  • very humid climate or a lot of precipitation
  • too shady location
  • missing waste
  • weakened immune system of the crop due to lack of fertilization, incorrect location or other diseases
  • Leaves that are left behind

Fallen leaves can also be a risk factor for the disease or cause the fungal spores to spread. The spores overwinter on the fallen leaves and can spread from here by the wind or insects.


The best way to prevent soot build-up is coordinated care and the right choice of location. These include:

  • a sunny, airy location
  • adapted watering in which the leaves are not wetted
  • sufficient distance between plants
  • regular waste
  • Remove fallen leaves as soon as possible and dispose of accordingly
  • Fertilize plants sufficiently to strengthen their resistance

Here, too, the foliage is of particular importance. Whether it falls off or is cut off, if there is any suspicion or the presence of soot, it must be destroyed or disposed of in the residual waste. Otherwise, the spores from the compost could spread again in the garden and infect other plants.

Prevention can also include choosing resistant varieties of roses. The selected cultivars should be resistant or at best resistant to typical rose diseases. These include:

  • Aachen Cathedral
  • Alpha Meidiland
  • Angela
  • Beautiful
  • Damn it
  • Dortmund
  • Scented gold
  • Fire magic
  • Yellow Dagmar
  • Medusa
  • Snowflake
  • Super Execelsa
  • The Fairy
  • White Cockade

Home remedies

If the soot has once attacked a rose, an appropriate remedy or countermeasure can be used to try to combat the infection. We have put together the x best home remedies and measures:

1. Verschnitt

As soon as signs of soot build-up are noticed, the affected leaves and plant sections should be removed. The chosen cutting tool – a sharp knife or well-cutting scissors – must be thoroughly disinfected after use. Otherwise, the spores could be transferred to other parts of the plant or vegetation the next time they are cut.

2. Potash fertilization

A fertilization with a strong emphasis on potash and low in nitrogen strengthens the plant and can be used both for prevention and control.

3. Horsetail broth

Horsetail broth or manure is rich in silica. Silica can help fight fungal diseases on plants.

4. Beinwellbrühe

It strengthens the plants and can thus increase their resistance. This makes it suitable for prevention as well as supportive treatment in combating.

5. Garlic broth

Garlic broth is a proven remedy for fungal infections in plants. It can be grated and diluted with water or briefly boiled in it. The affected plant is then sprayed with the solution.

Tip: The products must be used several times on the roses. Time intervals of between three and seven days and repetition at least three times are ideal.

Alternative means

If the specified agents are not sufficiently effective, fungicides can be used. These are available in stores as special agents for roses, among other things.

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