If the lilac (bot. Syringa vulgaris) loses its leaves in autumn, there is no reason to worry. Losing leaves in autumn is completely normal, as the shrub is only summer green and gradually goes into hibernation from October onwards.
Why is my lilac losing its leaves?
Answer: Lilacs naturally lose their leaves in autumn. In summer, leaf loss can be attributed to lack of water, waterlogging, disease or pest infestation. Watering, pruning, relocation or treatments may help, depending on the cause.
These causes can be behind leaf loss
It looks different when the lilac sheds its leaves in the middle of summer or doesn't get any at all. In this case there is a serious problem, the cause of which should be found and eliminated.
Water shortage
Especially in hot, dry periods, a lack of water in lilacs quickly becomes noticeable: the shrub initially lets its leaves hang and gradually dries out. As the process progresses, the leaves are shed to reduce evaporation. The ornamental tree has very large leaves that condense a lot of water. You can remedy a lack of water by watering vigorously, although you should not wet the leaves - otherwise mildew could settle on them.
Waterlogging
But before you reach for the watering can, check again whether lack of water is actually the correct reason for the leaves dropping. More often, excessive moisture or even waterlogging is the cause, as a result of which the roots rot and can no longer adequately supply the above-ground foliage. If the damage has not progressed too far, you may be able to save the shrub by cutting it back and moving it to another location, but in many cases clearing is unavoidable.
Diseases
If the leaves turn brown or develop brown spots before they are shed, then a fungus is the cause. In addition to a fungicidal infection, bacteria (e.g. wilt bacteria or the more common lilac disease) can also be behind it. To treat the lilac, you must cut the affected parts of the plant back to the he althy wood and collect all the leaves that have fallen to the ground. These should either be disposed of with household waste or burned, but under no circumstances should they end up in the compost.
Pest Infestation
The larvae of the lilac leaf miner feed on the leaves of the lilac. You can initially recognize an infestation when the leaves develop brown spots, curl up, dry out and finally fall off. In the current year, no treatment other than picking off infected leaves is necessary. The following year you can spray neem to encourage leaf growth.
Tip
If lilacs are not cut for many years, they will gradually become bald. This is not a sign of an illness, but rather a completely normal sign of aging. The shrub can be rejuvenated by careful pruning.
