Brown Spots on the Leaves of a Magnolia Tree

Magnolia tree foliage is susceptible to fungal infection.

Magnolia (Magnolia spp.) is a large group of evergreen shrubs and trees adapted to U.S. Department of Agriculture zones 6 to 9. Magnolias grow 15 to 80 feet tall and bloom with glossy, fragrant flowers. The dark green leaves are up to 2 feet long. Fungal infections lead to the appearance of brown spots on foliage.

Identification

Magnolia tree foliage is susceptible to phyllosticta leaf spot disease caused by the Phyllosticta fungi. The disease is more common in summer. Fungal growth is favored by fog, heavy dew and humidity and light, frequent rain.

Damage

The disease is characterized by the appearance of irregular to circular, large or small spots on foliage. The spots range in color from gray to brown to black and often have defined margins. In cases of severe infection, premature yellowing and leaf drop occurs. Black fungal fruiting bodies in the form of specks develop in the center of older spots.

Management

Keep the plant area clear of foliage and debris to avoid spread of fungal spores. Avoid watering plants with overhead sprinklers. Water plants earlier in the day to allow foliage to dry. The use of fungicide is usually not required.

References

• "Care Free Plants"; Reader's Digest Association; 2002
• Alabama Cooperative Extension: Fungal Leaf Spot Diseases
• University of California Extension: Magnolia