Oleander is a beautiful plant that requires little care and blooms profusely throughout the summer. However, the exotic, unfortunately, is not particularly resistant to disease and is often affected by bacteria and fungi. We list the most common oleander diseases.
Table of Contents
- Oleander diseases: The tub plant is susceptible to fungal and bacterial infestations
- Oleander gets yellow leaves: Dry rot as a possible cause
- Oleander diseases: Oleander canker is a common cause of brown leaves
- Why does the oleander get brown spots? It is sooty mold
- Oleander diseases: White leaves are a sign of powdery mildew
Oleander diseases: The tub plant is susceptible to fungal and bacterial infestation
In Mediterranean countries with a hot summer and warm humid winter, such as Morocco and Spain, the oleander grows outdoors without any problems. In this country, however, it is only suitable for container growing, as it cannot survive the cold winter months in the garden. As a container plant, however, it is susceptible to pests, fungi and bacteria. But it is not always a disease or infestation.
Special case: your oleander gets yellow leaves? Lack of water as a possible cause
Yellow leaves that fall off do not necessarily indicate a disease. In most cases, it is a care error or leaf renewal. Especially in hot weather, the soil can dry out. However, lack of water or over-fertilization can make the exotic poorly thrive and react sensitively with leaf drop.
A sick oleander, on the other hand, not only yellow leaves, but also notice brown spots, black or white spots. If you notice discoloration, thickened buds or buildup on the leaves, check the underside for pests as well. Scale insects and spider mites also leave evidence in the form of a thick sticky substance on the underside of the leaves.
If you do not notice any pests on the oleander and in the pot, then it may 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 not cared for properly. Especially if you water the tree from above and the leaves stay wet for a long time afterwards, or if the humidity is exceptionally high in the summer, the tree can get dry rot.
The disease begins with yellow leaves, on which black spots slowly form. The affected parts of the plant dry up and die. Initially, the upper leaves and shoots are affected. However, if you do not treat the disease in time, then the fungi can also attack the trunk of the tree and the whole woody plant 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, it is most likely a dangerous disease – oleander canker. The pathogen in this case is a bacterium that is usually transmitted by pests. The affected plant has many invisible cracks on the leaf surface, which are entry points for the bacteria. In the beginning, the disease is noticeable by yellow spots near the leaf veins.
What helps against oleander canker?
You can not treat oleander canker, but it helps if you strengthen the plant with proper watering and fertilizing. If it is infested with aphids, be sure to control the pests. It also helps if you cut off the infested plant parts as soon as possible and dispose of them with household waste. It is best to cut into the healthy wood and disinfect the pruning shears afterwards.
Why does the oleander get brown spots? It is sooty mold
Sooty mold, still known as black spot disease, is also caused by fungi. They are spread by watering water (when the plant is watered from above). Wet leaves and interfaces that are not clean are the entry points for the fungi. Aphid infestation can also promote the disease. The pests excrete 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 by many brown spots with yellow edges on the leaves and shoots. The affected plant loses leaves and hardly forms flowers.
Sooty mold is controlled with special fungicides. The treatment is carried out in several stages. First, all diseased parts of the plant are cut off. Then the oleander is treated with fungicide twice, 14 days apart.
Oleander diseases: White leaves are a sign of powdery mildew.
Unlike other fungi that spread in warm and humid weather, powdery mildew prefers dryness. The first sign of the disease is a white powdery coating that first stands 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.
Against powdery mildew helps a simple home remedy: raw milk. Put 200 ml of milk in a one-liter spray bottle and dilute it with 800 ml of water. Use it to treat the plant with the solution every three days until the coating disappears
Special case: white spots 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 spots on the leaves.
Oleander has sticky leaves? Blame it on scale insects
But even before you notice the many white dots, you’ll notice the sticky leaves. Natural remedies such as orange oil will help against scale insects.
Spider mites on oleander
An infestation of spider mites on oleander is also easily recognizable by the many small white dots. The leaves then begin to wilt and die. A mixture of water and vegetable oil proves very effective against the pests.