Oleander Diseases: Recognizing and Treating Symptoms

Unfortunately, the oleander is not completely resistant to diseases either. We show the most common diseases, their symptoms and methods of combating them.

oleander (Nerium oleander) are very strong and hardy bushes. In countries like the USA or South Africa, they even grow invasively and displace native species. However, in a tub or pot, where the plant has to be kept in due to the cold winters here, it is a lot more susceptible. In any case, the best precaution is that your oleander is doing well. Because a strong oleander also has a healthy immune system and is much more resilient.

If the leaves of the oleander turn yellow and fall off in summer, this is not immediately a reason to panic. Especially in the hot season, the oleander likes to carry out an all-round renewal. Although the shrub is evergreen, its leaves also have to be replaced every two years. In this case, however, new leaves should already be on the way. Other causes of yellow leaves can be lack of water or light. It is probably a disease if the leaves only change color at certain points and the yellow leaves have brown patterns. We list some of the most important diseases below.

Oleander canker: symptoms and control

A common disease that can unfortunately affect all oleander varieties is the so-called oleander canker. This is triggered by Pseudomonas-Bacteria that get into the sap of the plant and spread there. The result is stunted and bursting buds and flowers, often turning black. Infructescences do not develop on the affected shoots at all or only develop strangely stunted. Shoots also begin to develop outgrowths or burst open. As a result, the branches become unstable and break off.

Combat oleander cancer:

• Cut back severely affected shoots radically.
• If the shoots are not so badly affected, at least remove the affected inflorescences and infructescences.
• Keep your pruning tool clean and disinfect.
• Do everything you can to make your plant happy. tips for Oleander care get here.
• Dispose of the waste in the household waste. In the compost, the bacteria would remain in the soil. Burning is also not an option as oleander smoke is toxic.

Unfortunately, there is currently no treatment for oleander cancer. However, older oleander bushes in particular can cope with an infestation if you contain it through targeted pruning.

Oleander fire blight: symptoms and control

Fire blight is a dangerous bacterial disease that affects both fruit and ornamental crops. Since it spreads quickly and is particularly dangerous for fruit trees, there is an obligation to report this disease. Depending on the federal state, the infestation with fire blight must be reported either to the state office or to the state institute for agriculture. Information on this can be found on the websites of the state offices for agriculture in the respective states. Individual leaves and inflorescences suddenly die off starting from the stem and turn brown to black. Nevertheless, they do not fall off the plant, but stick to it. If you do not take any measures, the plant will die within a few weeks.

Measures to combat fire blight in oleanders:

• Rigorously cut back affected parts.
• Dispose of the accumulated green cuttings well packaged in the household waste; under no circumstances throw it in the organic waste bin or on the compost.
• Disinfect your cutting tools thoroughly with high-proof alcohol.
• Immediately separate the infested oleander from other fruit or ornamental trees in the area.
• Preparations containing microorganisms can help contain and prevent fire blight.

Dry rot in oleanders: symptoms and control

Dry rot is caused by a Ascochyta-Fungus triggered. Paradoxically, the reason is usually too high humidity or too much water from above. The oleander is particularly infested in the winter quarters, but rainy summers can also become a problem. In particular, dense oleander bushes that dry off poorly are susceptible.

Symptoms are brown and black spots on shoots and leaves. Particularly delicate parts of the plant are attacked first. As the name "dry rot" already suggests, affected areas look dry. The fungus gradually migrates to the base of the plant. Once it has reached this, the oleander dies.

Measures to combat dry rot in oleanders:

• Dry rot can be prevented with fungicides.
• Rigorously prune affected branches and shoots to the nearest unaffected fork; cut down to the healthy wood; spreading to the base must be prevented at all costs.
• Pay attention to the hygiene of your cutting tools.
• Dispose of infested shoots in the household waste.

Gray mold on oleanders: symptoms and control

Gray mold is less dramatic. It also occurs as a result of high humidity, i.e. in rainy summers or in winter quarters. However, mainly double-flowered species are affected, as they do not shed their flowers themselves. Therefore, remove all dried flowers from the shrub before putting them into winter quarters and during long periods of rain. Gray mold affects only the inflorescences and does not pose a serious threat to the plant itself. However, it can destroy the flowering in the next year.

Sooty mildew on oleanders: symptoms and control

Sooty mildew is the name given to the phenomenon when black deposits form on the leaves of the plant. In itself, however, sooty mildew is not a disease, but a consequence of aphids or scale insects. The transparent and sticky honeydew they secrete is colonized by fungi and turns black. This hardly harms the plant directly. However, the black discoloration impedes photosynthesis in the affected leaves and clogs the pores. However, sooty mildew can be easily wiped off with water. In stubborn cases, a highly diluted vinegar solution can also be used. However, you should take the lice seriously, because they can cause great damage.

Find out which ones here Pests on oleanders occur and how to counteract them.

To prevent diseases is particularly correct Taking care of your oleander what matters. In this article you will learn the most important information on this topic.