Certain diseases crop up in these areas that can cause avocado leaf drop. Mite pests and root rot both contribute to fallen leaves. Learning about what causes these diseases to occur and knowing how to prevent them ensures a healthy, fruit bearing avocado tree.
Persea mites attack avocado trees mainly in the state of California. These mites have eight legs and an oval shape. Certain mites, such as the avocado brown mite and six-spotted mite only wreck occasional havoc on avocado trees. Mites become a problem during the spring and summer months. These tiny insects grow to only 0.01 inches and their coloration is a mixture of green and yellow. Oftentimes, they have up to six dark spots on their abdomen.
Phytophthora root rot contributes to most of the problems that these fruit trees face concerning pest, diseases and premature, avocado leaf drop. Rehabilitating an avocado with root rot is difficult once the tree is diseased. Root rot forms in locations with a combined lack of soil moisture and inadequate drainage for the soil.
Trees displaying signs of root rot will have foliage that appears shrunken. Once the leaves have shrank, avocado leaf drop occurs.Tiny roots look weak, breakable and black in color. Roots that display these symptoms are most likely dead as a result of the disease. The leave on an avocado tree leaves' curl even when proper moisture fills the soil when root rot is present.
When mites feed on these fruit trees, the leaves change over to a brown color before dropping off. Webbed veins can show up on damaged leaves before avocado leaf drop takes place.
Under normal circumstances, natural methods control the spider mite population because other mites and insects are predators.The lady beetle (Stethorus picipes) is a spider mite enemy along with six-spotted thripes (Scolothrips sexmaculatus) that live on some avocado trees. These predators help to reduce the population of spider mites that are harmful to avocado trees.
Other methods of eliminating problematic spider mites include spraying the affected areas on the avocado tree with miticide (gets rid of mites). Removing as much dirt road dust around the trees as possible will help reduce the amount of mites on the avocado. This is achieved by oiling or paving the roads leading to and those in between the orchards. Misting home grown avocado trees reduces your chances of having issues with mites.
Start at the nursery to reduce the chances of the avocado tree becoming infected by root rot. Root rot tends to spread in plant and tree nursery stores. Select disease resistant avocados. Use nitrogen in moderation to help prevent root rot. However, do not over-spray with fertilizer. Animal manure is not good for avocado trees because it contains ammonia and sometimes salt. The avocado roots are sensitive to ammonia and salt.