Oleander is not only beautiful, but also very sensitive to various pathogens. These can be bacterial, but also fungicidal in nature. The clinical pictures listed here are particularly common in oleanders.
Too much moisture can lead to various fungal diseases
Blight (Ascochyta)
Dry rot or Ascochyta very often occurs on overwintered and thus weakened oleanders. However, the disease also occurs at the end of summer. Typically, infected parts of the plant first turn brown and then dry up and die.
You can do that
There is no effective fungicide against dry rot that has already broken out. You can only take preventive action by spraying the oleander with a commercially available agent before putting it into its winter quarters. If the disease has already broken out, only a strong pruning will help.
powdery mildew
Powdery mildew is also known as "fair-weather mildew" because this fungal disease develops primarily in warm summers. You can recognize an infestation primarily by the mealy-looking, white and wipeable covering. This can not only affect the upper side of the leaves, but also the shoots and flowers. Since the affected plant puts a lot of energy into fighting the parasitic fungus, both growth and the development of the flowers falter. Leaves and flowers turn brown and dry up as the disease progresses.
You can do that
Fortunately, powdery mildew can be fought quite easily. You can use commercially available fungicides for this, but you can also spray the affected plant with a mixture of fresh whole milk and water (mixed in a ratio of 1:10). However, already diseased parts must be cut back. However, this tried and tested home remedy only works with fresh milk, since the fungicidal microorganisms have been killed in preserved milk.
Gray mold (Botrytis)
This fungal disease, which is also very common on other plant species, occurs on oleanders primarily in autumn. The main cause is excessive moisture, which is why you should pay attention to dry leaves and shoots when putting them into winter quarters. The flowers are particularly affected, but leaves and shoots can also be affected. Diseased parts of the plant are covered with a grey-white coating and appear moldy.
You can do that
As a preventative measure, you should remove the dried-up flowers of the oleander before putting them into winter quarters. Also, always make sure that the plant is always in a light draft, so that a regular exchange of air is guaranteed.
tips
Above all, scissors help against all fungal diseases: cut back affected parts of the plant far into the healthy wood. However, you should wear gloves, because the oleander is poisonous.