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Avocado trees are evergreens that grow in the United States — thriving in Florida, California and Hawaii — and other tropical areas of the world. Mature avocado trees grow from 30 to 65 feet tall with leaves up to 16 inches long. The trees produce spherically-shaped, soft fruits that weigh up to 5 pounds. If a tree’s leaves develop a pale green or yellow tint, the plant could be in danger of root rot.
An avocado tree may be in danger of root rot if it develops brown or yellow spots on its leaves or if foliage falls prematurely. Although the tree is an evergreen, it may lose a few leaves when there is new growth. However, a thinning canopy, substantial loss of foliage or small branches is a sign of trouble. Root rot can occur on trees of all ages and sizes when soil is too wet. The pathogen, called Phytophthora root rot, can spread several types of fungal spores throughout the tree.
Relief - Can Avocado Trees Survive Root Rot?
Avocados, like other trees suffering from different forms of root rot, do not have a “cut and dry” method for saving them. The best way to avoid diseased trees is to plant healthy ones, according to the University of California’s Agricultural and Natural Resources department and the California Rare Fruit Growers organization. However, removing the tree from its diseased soil, cutting out damaged tissues and reducing water may give it a chance to “dry out.” Do not replant the tree in the same place. Actually, garden experts say diseased trees of any kind should be destroyed because the damaging fungal spores can travel to other plants.
Other Avocado Diseases
Dothiorella is a fungus that causes cankers on the tree’s trunk. Cercospora are brown spots with yellow halos that form on the avocado fruit, usually during the summer. Avocado scab affects the young leaves, twigs and fruit — it produces dark spots but doesn’t affect the quality of the fruits. Anthracnose is a fungus that rots the fruit. Powdery mildew develops under the leaves, mostly during dry periods. Verticillium wilt occurs when one tree branch seems to suddenly sag and hold on for several weeks. Sun blotch is a discoloration of twigs, leaves and fruits. Avocado trees with sun blotch should be destroyed.
When planting avocado trees, choose an area that has good water drainage — too much moisture in the soil will damage the cultivar’s root system. The pH value of loose, granular soil should be higher than 6. 2. Obtain healthy trees or clippings from a plant nursery to be sure the plants are disease-free. Never plant clippings from diseased trees because the fungal spores will contaminate the clean soil. Avocado trees can live in shade but only produce fruits when they are growing in full sun.