Owning an oleander plant can give a Mediterranean feel to your garden. The plant reaches heights up to 4 metres with dazzling blooms that range in colour from hot pink to soft creams and whites. Unfortunately, oleander plants are susceptible to a disease that causes leaves to turn brown, branches to droop and plant tissue to die. The name of this disease is "oleander leaf scorch" and the cause of the disease is a bacterium that goes by the name of Xylella fastidiosa.
Prune away any of the diseased tissue you find on the oleander. This includes leaves and whole branches. Removing the diseased branches and leaves will improve the overall health of the plant and better help it fight the disease. The best time to prune is immediately after the blooming season.
Examine the leaves and branches on a regular basis. Monitor the plant and make sure there are no new outbreaks of the disease. Check the plant at least once a week to catch new outbreaks before they get out of hand.
Cut the entire oleander tree down to the soil line if the oleander leaf scorch spreads to the greater part of the plant. When there is more infected tissue than healthy tissue, sometimes the only thing to do is remove all the tissue and let it grow all over again. It may seem a little frightening to cut down the oleander plant, but it may be the only way to replenish the healthy tissue.
Water the oleander plant thoroughly before you prune the plant for at least two weeks. Unfortunately, the symptoms of drought (brown leaves, drooping) can be mistaken for oleander leaf scorch. Water the plant and examine it for signs of improvement. If the plant improves, the culprit is most likely lack of water; if the condition persists, it is most likely oleander leaf scorch.
Burn the excess leaves and branches you cut off the oleander instead of putting them in a compost heap. This helps lower the chances of the disease spreading to other oleander plants in your garden.
There is no absolute cure for oleander leaf scorch. You can take steps to care for and prolong the life of the oleander once it has caught the disease, but it will eventually wither and die.