Brown leaf spots can be an indication of oleander cancer
Oleander cancer is caused by Pseudomonas bacteria that cavort in the sap of the shrub. Since in principle almost all oleanders are infected, an outbreak of the disease is not that unusual. The first signs of an outbreak are stunted flowers and buds that either do not break open in the first place or even turn black and then burst. In the further course brown spots appear on the leaves, which also break open. On the other hand, the typical cancerous growths appear on the shoots.
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Only scissors can help against oleander cancer
There is no cure for oleander cancer, except for one thing: sharp scissors. Cut away infected parts of the plant generously; if the infestation is severe, you can also place the affected oleander on the stick. That means you cut it off to just above the ground. As a result, the plant will sprout again healthily, but you will have to refrain from flowering for at least one year.
Other causes of brown spots
However, brown leaf spots do not always have to be an indication of oleander cancer, there are other causes as well. So-called leaf margin necrosis - this is characterized by a brown leaf margin and brown spots - is an indication of over-fertilization. Although this makes the plant look rather unattractive, it is otherwise harmless. Furthermore, incorrect wintering - especially if it is too dry and / or too warm - can lead to brown discoloration of the leaves. Make sure to water the oleander sufficiently in winter and to overwinter it at about 5 ° C and as brightly as possible.
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If, on the other hand, the leaves of the oleander tend to turn yellow, a lack of nutrients and / or water is the most likely cause.
