Content
- Black spots on oleander have different causes
- fungal infection
- Thyroid or aphid infestation
- Oleander Crab (Pseudomonas)
- Tips
Too much moisture can cause fungal infections
Black spots on oleander have different causes
Oleander is known to be very susceptible to certain diseases or infestation by pests. Even with so much effort, many a disease can hardly be avoided, because it is simply in it in almost every oleander and breaks out quickly under appropriate conditions. This type of oleander disease includes oleander cancers caused by the bacterium Pseudomonas, the first signs of which are often brown to black spots on the undersides of the leaves.
fungal infection
However, you do not have to fear the worst with every black spot, because in many cases black leaves are an indication of a more harmless fungal infection. This occurs particularly frequently when the leaves of the oleander get wet and can not dry off quickly enough, or when the oleander is too cool at high humidity for too long. For this reason, such black spots often appear during or after the wintering of the shrub.
Thyroid or aphid infestation
If the black of the leaves can be easily wiped off with your fingers, it is probably a Rußtaupilz. This is in almost all cases an indication of a pest infestation, mainly by aphids or scale insects. Both insects but a sweet secretion (the so-called "honeydew"), which in turn serves the Rußtaupilz as food. In order to be able to combat the black smoke fungus effectively, you must at the same time kill the causative pests. So make sure that the aphids and aphids do not feel too comfortable on your oleander, then the black smoke will soon be history.
Oleander Crab (Pseudomonas)
Oleander cancer is often manifested by knobbly growths on the shoots and black or dark leaf spots, which are surrounded by a bright edge. This disease is caused by Pseudomonas bacteria and is spreading rapidly. The disease is not necessarily fatal, but can only be treated by a vigorous pruning.
Tips
If you are unsure about the cause of the black spots on the leaves, wait and see the oleander - you can still cut it off if it does.