When Do Avocado Plant Leaves Fall?

Identification

• Avocado trees are susceptible to dematophora root rot, also referred to as rosellinia root rot. The disease, caused by dematophora necatrix, is cited as a serious avocado disease by the University of California Extension. The soil-borne fungus persists for extended periods in soil.

Damage

• The disease is characterized by the appearance of yellowing foliage and shriveling fruit. Infected trees stop producing fruit and roots start to decay. This is accompanied with defoliation. The fungus grows in the form of white cotton or mycelia, and covers the roots. With disease progression, the mycelia grows upward through the tree under the bark and lower trunk areas. Trees infected with fungus die completely within three years.

Control

• No fungicidal control options exist for disease; remove infected trees early and entirely with roots to minimize spread of infection. Use resistant tree varieties, especially in areas with known prior cases of infection. Plant in well-drained soil. The University of California Extension recommends solarizing or fumigating soil before planting as a preventative strategy.