Oleander is not only beautiful, but also very sensitive to various pathogens. These can be bacterial or fungicidal in nature. The diseases listed here are particularly common in oleander.
How can you combat and prevent oleander fungal infestation?
Oleander fungus can cause dry rot, powdery mildew and gray mold to occur. To combat this, cut back affected parts of the plant, ensure there is a draft and apply fungicides or a milk-water mixture. As a preventive measure, oleander can be sprayed before putting it into winter quarters.
Dry rot (Ascochyta)
Dry rot or ascochyta very often occurs on overwintered and therefore weakened oleanders. However, the disease also occurs at the end of summer. Typically, infected plant parts initially turn brown, then dry up and die.
You can do this
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 product available from specialist retailers 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 mainly develops in warm summers. You can recognize an infestation primarily by the floury, white coating that can be wiped off. This can affect not only the tops of the leaves, but also the shoots and flowers. Since the infected plant puts a lot of energy into fighting the parasitic fungus, both the growth and the formation of the flowers stop. Leaves and flowers turn brown and dry up as the disease progresses.
You can do this
Fortunately, powdery mildew can be controlled quite easily. To do this, you can use commercially available fungicides, 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, parts that are already diseased must be cut back. However, this tried and tested home remedy only works with fresh milk, as the fungicidal microorganisms have been killed in preserved milk.
Grey 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 moving them into winter quarters. The flowers are primarily affected, but leaves and shoots can also be affected. Diseased plant parts are covered with a gray-white coating and appear moldy.
You can do this
As a preventive measure, you should remove the dried flowers of the oleander before putting them into winter quarters. Also always make sure that the plant is always exposed to a slight draft so that regular air exchange is guaranteed.
Tip
Scissors are the first thing that helps against all fungal diseases: cut affected parts of the plant back to the he althy wood. However, you should wear gloves because the oleander is poisonous.