In terms of plant diseases, the summer lilac is quite resistant and stays healthy as long as it feels comfortable in its location and is well cared for. However, waterlogging in particular - caused by persistent bad weather, for example - can quickly lead to an infection. In addition, the only partially hardy wood often freezes back in cold winters, but drives out again after pruning.
Late frost can cause disease-like damage to summer lilac
Identify and treat frost damage
Frost damage probably occurs on every summer lilac. In particular, the shoots of Buddleja davidii, which is considered to be reasonably hardy, quickly freeze back in the event of frost. This is not a problem as long as the roots of the shrub are not affected. In early spring (from around the end of March) simply cut back the frozen parts of the plant, if possible right into the healthy wood. You can use the thumbnail sample to quickly determine which parts of the bush are still alive - if the layer under the bark is still green, the plant sap is still flowing here. After pruning, the buddleia will most likely sprout again.
Problematic in humid summers: downy mildew
Downy mildew, which often occurs in humid, rainy summers, is more problematic. This is a fungal disease characterized by a white-grey patch of fungus on the underside of the leaves and yellow spots on the upper side. Young shoots can also be affected. In the event of an infestation, it is important to act as quickly as possible to prevent it from spreading:
- Cut off all affected parts of the plant.
- Do not dispose of them in the compost, only with household waste.
- Spray the shrub with a field horsetail decoction that you have made yourself.
- Stop giving nitrogenous fertilizer.
- In the event of a severe infestation, fungicides from specialist retailers approved for private gardening will help.
Prevent downy mildew by only watering the buddleia over the root disc if necessary and not irrigating it. In addition, an airy location with a sufficiently large planting distance can help, because the leaves dry off faster here after a downpour.
tips
Of course, the summer lilac is also attacked by pests if it has been weakened by incorrect care or an unsuitable location. Above all, aphids, leaf miners or gall mites feel comfortable on such a plant. You can prevent this by setting up an insect hotel (€11.33) with beneficial insects near the flowering bushes.