Garden Tips

Diseases of roses - 4 diseases

Diseases of roses - 4 diseases

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The rose, the queen of flowers, can be found in almost every garden. And there are certainly diseases in the roses in every garden that affect these pretty flowers.

If a rose is infested with black soot, the leaves turn black

A garden without roses is hard to imagine. It is all the more annoying when their beauty is destroyed by diseases. Powdery mildew, downy mildew, rose rust and star soot hobby gardeners particularly like to annoy by spreading on the roses. These are leaf diseases caused by a fungus. You can certainly do something to prevent an infestation, but sometimes it's just too late for it. Then it only helps if you act quickly.

How to combat mildew and Co.

❖ Powdery mildew:

These mushrooms don't stop at a rose. If roses are infected by this fungus, then the shoots and the leaves are covered with a white coating. The leaves then turn brown, curl up and fall off. The fungus spreads particularly quickly in dry and warm weather in combination with nightly dew.


Affected areas should be removed immediately and generously. Then mix one part of whole milk with eight parts of water, place in a spray bottle and spray the infested roses with the mixture once a week. The microorganisms in the milk not only fight the fungus, they also help the rose to develop a kind of resistance to the fungus.

Alternatively, you can spray the infested plant with garlic stock (recipe here) or nettle slurry (recipe here). Also pay attention to more resistant varieties when planting.

❖ Downy mildew:

The leaves get reddish-brown spots on the top. As a result, mold forms. The leaves also fall off in this disease. In addition, the buds often dry up.


First remove all infected plant parts. In particularly severe cases, it may even be advisable to remove the entire plant from the garden straight away. This will prevent the fungal disease from spreading to other plants. With this type of mildew you can sprinkle the roses again with a milk-water mixture. But it also helps a horsetail brew that you have to spray on the plant every other day. Soak 1 kg of horsetail in 10 liters of water for 24 hours and then bring to the boil for 30 minutes.

❖ Rose rust:

This disease manifests itself in red or yellow spots on the top of the leaves. However, the spore bearings are located on the underside of the leaf. Dark spores later escape from it, which are scattered by the wind and spread to other plants. In the event of heavy infestation, the rose sheds its leaves.


Immediately remove the infected leaves. You can then spray the roses with field hors stock every two days. If that doesn't help, then you have to use a fungicide. We recommend e.g. CELAFLOR Saprol Rose Mushroom Free (available here for example). It is best to always follow the manufacturer's instructions when using it.

❖ Star soot thaw:

This fungal disease causes irregularly shaped gray-black spots on the leaves. In addition, the rose petal near the spots is always colored yellow. If there is a heavy infestation, the roses will even shed their leaves.


Remove all affected parts of the plant and any leaves that have already fallen. The fungus hibernates in the leaves on the ground and thus spreads further. Then you can spray the roses with garlic stock or field horsetail. If this does not help, you have to use a fungicide. Here, too, you can fall back on CELAFLOR rose-mushroom-free Saprol. However, COMPO Duaxo Rosen is also mushroom-free (e.g. available here). Again, follow the manufacturer's instructions.

Important: Dispose of infected plant parts in the residual waste

Always dispose of the infected plant parts in the residual waste, because fungi can overwinter in the plant parts and spread further in the garden. Therefore, never put the affected parts on the compost. Also clean all garden tools and planters. This also applies to trellis, privacy fences, etc.