The magically beautiful oleander with long, dark green leaves and delicate flowers is a real feast for the eyes. So it's no wonder that this shrub is often cultivated as an ornamental plant. Since the rather demanding plant is preferably kept in pots due to its lack of winter hardiness, brown spots on the leaves - often due to care errors - are not uncommon. But they can also be a symptom of the widespread oleander cancer.
Why does my oleander have brown spots on the leaves?
Brown spots on oleander leaves can indicate oleander cancer, over-fertilization or incorrect overwintering. If you have oleander cancer, remove infected plant parts generously. If over-fertilization occurs, reduce the amount of fertilizer and if wintering is incorrect, ensure adequate watering and cool, bright storage.
Brown leaf spots can be an indication of oleander cancer
Oleander canker is caused by Pseudomonas bacteria that live in the sap of the shrub. Since almost all oleanders are infected, an outbreak of the disease is not that unusual. The first sign of an outbreak is stunted flowers and buds that either don't open at all or even turn black and then burst open. As the disease progresses, brown spots appear on the leaves, which also break open. The typical cancerous growths can be seen on the shoots.
Only scissors help against oleander cancer
There is no cure for oleander cancer, except for one thing: sharp scissors. Cut off infected parts of the plant generously; if the infestation is severe, you can also put the affected oleander on the stick. This means you cut it down to just above the ground. As a result, the plant will sprout again he althily, but you will have to avoid flowering for at least a year.
Other causes of brown spots
However, brown leaf spots do not always have to be an indication of oleander cancer; other causes are also possible. A so-called leaf edge necrosis - this is characterized by a brown leaf edge and brown spots - is an indication of over-fertilization. Although this gives the plant a rather unsightly appearance, it is otherwise harmless. Furthermore, incorrect wintering - especially if it is too dry and/or too warm - can lead to brown discoloration on the leaves. Make sure to water oleander sufficiently even in winter and to overwinter it at approx. 5 °C and as brightly as possible.
Tip
If the leaves of the oleander turn yellow, a lack of nutrients and/or water is the most likely cause.
