Insects & Diseases of Citrus Trees

Citrus trees are deciduous fruit trees that include the grapefruit, lemon, lime and orange variations. These tropical trees thrive on warm climates, nutrient-rich soil and ample amounts of water. Even with routine maintenance and care, however, the citrus tree can become the target of insects and disease. While some of these predators only cause disfiguration, some can injure and eventually kill the tree, if left untreated.


Aphids are tiny insects that suck the sap from the foliage of the citrus tree. While the feeding of a few aphids on the citrus tree causes little change to the tree, an infestation of aphids can cause drastic damage to the tree, including leaf and branch drop, discoloration and dieback. Insecticide treatment can control the infestation of the citrus tree, as well as the surrounding area.

Citrus Whitefly

The citrus whitefly is a nearly microscopic insect that feeds on the underside of the citrus tree's foliage. Unlike the aphids, the citrus whitefly makes its home in the citrus tree. Infestation of the citrus whitefly causes the tree's leaves to curl and leaves a buildup of honeydew, which develops into a mold substance. Though the adult whitefly is somewhat difficult to control, several treatments of insecticidal spray designed for whiteflies will control the younger population.

Citrus Thrips

Citrus thrips are tiny insects that attack the foliage and young fruit of the citrus tree. These orange and yellow insects reproduce in the fall, and their eggs hatch in the spring, causing continual infestation when left untreated. Infected trees have distorted and curled foliage, buds and fruit, and infected areas may take on a grayish color. An insecticidal treatment can correct the issue with several biweekly treatments.

Greasy Spot

Greasy spot is a fungal disease that attacks the foliage of the citrus tree. This disease causes the appearance of brownish yellow spots on the underside of the foliage, followed by a significant leaf drop. Infected fruit will show small greasy spots and lesions, and will generally appear during the summer months. Greasy spot is controlled with regular collection and disposal of fallen and infected foliage and branches, along with copper spray treatments.

Root Rot

Root rot is a soil-borne fungal disease that attacks the root system of the tree. Attacking the tree internally from the ground up, root rot's initial symptoms include darkened and deadened trunk areas near the surface. As the disease penetrates the tree, the tree's branches, foliage and fruit will suffer damage, many times leaving unsightly cankers behind. Treatment of root rot requires fungicidal control, as well as removal of infected areas and disposal of any dropped or removed debris.

Keywords: citrus tree diseases, citrus tree insects, soil-borne fungal diseases, aphids

About this Author

Charmayne Smith is a business professional. She has worked in management for successful organizations since 1994, and her writing career began with her business career. Her business has successfully assisted many clients with start-ups, development, and expansions. She has a bachelor's degree in business and has published with Identity Theft Chat, Garden Guides, eHow, Travels, Associated Content and others.