White Spots on Magnolia Tree Leaves

Stately magnolias are prone to few diseases.

Stately magnolia trees are exceptionally healthy and hardy and prone to very few diseases and pests. Occasionally you may notice that the leaves of a magnolia tree have white spots. Thankfully these are easily treatable.

Potential Sources

Magnolia trees that develop white spots on their leaves are most likely suffering from a plant fungus known as powdery mildew. Powdery mildew appears as white, powdery spots on the surface of the leaves and is relatively harmless to an otherwise healthy tree. Another cause of white spots is an insect infestation known as false oleander scale.

Causes

Powdery mildew is most often caused by prolonged periods of high humidity and warm temperatures. There is very little that can be done to prevent your tree from contracting this fungus if these weather conditions exist.

False oleander scale is most often found in plants in the southern part of the United States and is extremely common in Florida.

Treatment

Powdery mildew is reasonably easy to treat. If the infection is fairly localized and within easy reach, removing the infected leaves and burning them will effectively eradicate the fungus. If you cannot reach the infected area, you can spray your magnolia tree with a fungicide.

False oleander scale can be treated by spraying the affected leaves with a horticultural spray oil, which will suffocate the insects.

References

• Cornell University: Powdery Mildew
• University of Florida: False Oleander Scale