The oleander is a beautiful plant that requires little care and blooms profusely all summer long. Unfortunately, the exotic is not particularly disease-resistant and is often attacked by bacteria and fungi. We list the most common oleander diseases.
Oleander diseases: The potted plant is susceptible to fungal and bacterial attack
In Mediterranean countries with a hot summer and warm, humid winter, such as Morocco and Spain, the oleander grows easily outdoors. In this country, however, it is only suitable for keeping in containers because it cannot survive the cold winter months in the garden. However, as a container plant it is susceptible to pests, fungi and bacteria. But it is not always a disease or an infestation.
Special case: Your oleander is getting yellow leaves? Lack of water as a possible cause
Yellow leaves that fall off do not necessarily indicate disease. In most cases it is a care error or a leaf renewal. The soil can dry out, especially in hot weather.Lack of water or over-fertilizationHowever, the exotic can thrive poorly and reacts sensitively with leaf loss.
A sick oleander, on the other hand, not only has yellow leaves, but also brown spots and black or white dots. If you notice discoloration, thickened buds or build-up on the leaves, check the underside for pests too. Scale insects and spider mites also leave traces in the form of a thick, sticky substance on the underside of the leaves.
If you don't notice any pests on the oleander or in the pot, then it could be a disease. We list several possible causes.
Oleander gets yellow leaves: dry rot as a possible cause
Dry rot is a fungal disease that many oleanders suffer from if they are not cared for correctly. Especially if you water the tree from above and the leaves remain wet for a long time afterwards, or if the humidity is exceptionally high in summer, the tree can suffer from dry rot.
The disease begins with yellow leaves, which then slowly develop black spots. The affected plant parts dry up and die. The upper leaves and shoots are initially attacked. However, if you do not treat the disease in time, the fungi can also attack the tree trunk and the entire tree can die. Dry rot is controlled with fungicides.
Oleander Diseases: Oleander canker is a common cause of brown leaves
If the oleander has yellow to dark brown leaves and black growths, then it is most likely a dangerous disease - oleander canker. The pathogen in this case is a bacterium, which is usuallytransmitted by pestsbecomes. The infected plant has many invisible cracks on the leaf surface, which are entry points for the bacteria. Initially, the disease manifests itself as yellow spots near the leaf veins.
What helps against oleander cancer?
You can't treat oleander canker, but it helps if you strengthen the plant with proper watering and fertilizing. If it is infested with aphids, you should definitely combat the pests. It also helps if you cut off the affected plant parts as quickly as possible and dispose of them with household waste. It is best to cut into healthy wood and then disinfect the secateurs.
Why does the oleander get brown spots? It's sooty mold
Sooty mold, also known as black spot disease, is also caused by fungi. They are spread through irrigation water (when the plant is watered from above). Wet leaves and unclean interfaces are the entry points for the fungi. Also oneAphid infestationcan promote the disease. The pests secrete a sticky substance with a high sugar content. This substance provides food for the fungi and allows them to spread.
Initially, the disease is noticeable as many brown spots with a yellow border on the leaves and shoots. The affected plant loses leaves and hardly produces any flowers.
Sooty mold is controlled with special fungicides. Treatment takes place in several stages. First, all diseased plant parts are cut off. Then the oleander is treated with fungicide twice with an interval of 14 days.
Oleander Diseases: White leaves are a sign of powdery mildew
Unlike other fungi that thrive in warm, humid weather, the powdery mildew fungus prefers drought. The first sign of the disease is a white powdery coating that initially appears as spots on the leaves. Then the whole leaves turn white and dry up. The flowers also die and fall off before they have opened.
A simple home remedy helps against powdery mildew: raw milk. In a one liter spray bottle, add 200 ml of milk and dilute it with 800 ml of water. Treat the plant with the solution every three days until the plaque disappears
Special case: White dots on oleander indicate a pest infestation
Discolored leaves do not necessarily indicate disease. Pests such as scale insects can also be identified by the many white dots on the leaves.
Oleander has sticky leaves? Scale insects are to blame
But even before you notice all the white dots, you'll notice the sticky leaves. Natural remedies such as orange oil help against scale insects.
Spider mites on oleander
AInfestation with spider miteson oleander can also be easily recognized by the many small white dots. The leaves then begin to wither and die. A mixture of water and vegetable oil proves to be very effective against the pests.
