As robust as lilacs are usually, the shrub is sensitive to fungal infections. For this reason, the wood should always be in an airy, sunny location that is not too damp. In addition, only thoroughly sharpened and disinfected instruments should be used when cutting - infections often spread via dirty pruning shears or saws.

Stains on the leaves often indicate a fungal attack

Which signs indicate a fungal attack

You often notice a fungal attack first by a change in the leaves. These suddenly develop brown or yellow spots, dry up completely and eventually simply fall off. Some fungi also cause whitish or gray deposits, which can affect the young shoots as well as the leaves. Depending on the cause of the infection, the shoots will eventually wither and individual branches will die off. Other fungi (for example honey fungus) mainly attack the roots. Not every fungal infestation requires urgent treatment, nor does every infection threaten the health and survival of the affected lilac.

Which fungi most commonly affect lilacs?

Mildew fungi (Microsphaera syringae), for example, are comparatively harmless, even if the white or gray fungal growth on the leaves and shoots looks very unattractive. Gray mold, which is caused by Botrytis fungi, also causes a gray lawn of fungi. Other common fungal diseases on lilacs are these:

  • Galena disease: caused by Chondrostereum purpureum, often only clearing helps
  • Ascochyta leaf spot disease: caused by Ascochyta syringae, recognizable by large gray leaf spots edged with brown and shoot rot
  • Lilac blight: caused by Gloeosporium syringae, large parts of the leaf blade show brown spots
  • Leaf scorch: caused by Heterosporium syringae, large grey-brown leaf spots, often with a velvety surface
  • Leaf spot disease: Septoria syringae causes yellow-brown spots
  • The sac fungus Phyllosticta syringae damages both leaves and shoots.
  • Wilt disease: caused by various Verticillium fungi, characteristics: brown leaves, shoot wilt, leaf fall

What to do in the event of a fungal infestation?

The different fungal infections are basically all treated in the same way:

  • Remove the affected leaves and dispose of them with household waste.
  • Sweep up fallen leaves carefully to prevent reinfection.
  • Cut back the affected parts of the plant deep into the healthy wood.
  • Treat the lilacs with a strengthening decoction of field horsetail, tansy or garlic.
  • You can put this on yourself and spray the shrub regularly with it.

In the case of a lilac that was already infected the previous year, the spray treatment should already be applied at the time of budding in order to avoid re-infestation - many fungi overwinter in the form of spores near or on the plants.

tips

In the case of a severe infestation, copper-containing fungicides from the garden store can also help.

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