What are the diseases and parasites of oleander?
Very pretty with its colorful flowers and shiny green foliage, the oleander is unfortunately a rather fragile flowering shrub, which can become the target of many pests and diseases in a garden (or grown in pots on a terrace or balcony!).
here are the main diseases of oleander, and especially how to diagnose their presence on your plant:
- Aphis nerii, also known as oleander aphid. In spring, summer or autumn, this pest insect loves to land on the leaves of oleander, in order to feed on the sap of the latter. An oleander that undergoes repeated attacks from aphids will recognize itself easily: its leaves will tend to curl on themselves, then become all black before falling. But that's not all: aphids can also transmit 2 diseases to the oleander: bacteriosis and sooty mold.
- The mealybugs. Mealybugs are biting insects that, like aphids, feed on the sap of oleander. Deprived of part of its sap, the oleander, if it undergoes the attack of many mealybugs (there are different species), will not be long in perishing. Scale insects can also transmit a terrible disease to oleander: sooty mold.
- Theyellow spider. Fearsome once the summer season comes, the yellow spider hides under and on the leaves of the oleander to feed on its sap. This results in an oleander whose foliage changes from green to gray, and which loses its vigor. We spot the yellow spider with its web that it weaves around the leaves of the shrub.
- The sooty mold. Sooty mold is a oleander disease which develops when the shrub is attacked by a large number of mealybugs. Indeed, after being nourished by the sap of the shrub, the latter will secrete a viscous honeydew which will gradually cover the fungus - which will visually result in a fine blackish film on the leaves. Even if the colonization of the oleander by the scale does not necessarily lead to the death of the plant, it weakens it enormously and causes it to wither.
- The blight. Bacteriosis is an oleander disease that can be transmitted either through insects or through humans when treating their plants. Visually, bacteriosis results in the appearance of black necrosis (chancres), especially on the young branches of the shrub, which will deform them and prevent the oleander from developing properly.
Oleander diseases: how to fight them?
- For fight aphids, you can either buy ladybugs that love to feast on these insects, or spray on the oleander ecological solutions based on black soap, nettle manure or fern frond manure for example.
- For to heal an oleander attacked by mealybugs, an effective solution is to remove the scale insects by hand using a cloth coated with a few drops of dishwashing liquid. Indeed, this insect is very resistant to water. It is therefore with more oily products that it is possible to combat it. This solution can work if your oleander is a small plant that is not yet fully infested with mealybugs.
- For prevent yellow spider to weave its canvas on the leaves of your oleander, do not hesitate to use rapeseed oil or to rinse the leaves of the tree with soapy water.
- For prevent your oleander from being affected by sooty mold, you can spray Bordeaux mixture as a prevention. If, on the other hand, the oleander is already affected by the fungus, try to shower it for several days with a mixture of water and black soap.
- The bacteriosis being very difficult to treat, it is advisable to remove the affected parts of your oleander and then burn them.