Why Are the Leaves on My Avocado Tree Turning Brown?

Avocado trees thrive in tropical weather.

Avocado trees (Persea americana Miller) are native to tropical America and thrive in tropical and subtropical weather. Evergreen avocado trees grow up to 30 feet tall with 3- to 16-inch-long elliptical foliage. A fungal disease causes brown foliage on trees.

Identification

Avocado trees are susceptible to dothiorella leaf and stem blight caused by Botryosphaeria spp. and Fusicoccum spp. The disease is common in regions with hot weather. Underwatered trees are more prone to the infection.

Damage

The disease is characterized by drying, brown foliage that remains attached to trees. Small branches are also killed. Fruit on affected branches shrivels and turns black. Infected foliage on healthy branches displays brown patches on tips and at leaf margins. Leaves on unaffected branches are often necrotic or have yellow patches.

Control

Prune and remove all affected tree areas. Dispose of debris away from trees as it could harbor fungal spores. Pay attention to sanitation around trees and keep trees well irrigated, especially during hot weather. Chemical control options include the use of copper hydroxide.

References

• University of Florida Extension: Avocado Growing in the Florida Home Landscape
• University of California Extension: Dothiorella Leaf and Stem Blight