Pests & Diseases of the Citrus Tree

Citrus trees are desirable for their beautiful, fragrant blooms and tasty, versatile fruit. Many trees come in dwarf varieties, making them a perfect specimen, patio or even indoor plant, according to Colorado State University. These attractive trees are not without problems, however. They can suffer from a number of diseases and insect pest infestations.

Common Insect Pests

Citrus trees can suffer from aphids, mealybugs, mites and scale, which are seen on both indoor and outdoor trees. These insects rarely harm the tree, but they can be unsightly and cause some defoliation. Minor infestations can be rinsed off with a strong stream of water. Major infestations might need to be treated with insecticidal soap or even chemical sprays. Always choose a spray safe for citrus trees and follow the directions for application according to the size of your tree.

Citrus Canker

Citrus canker is a problem in citrus trees because it is a bacterial disease, and a very contagious one at that. The disease spreads on wind, water, contaminated pruning or gardening tools, and even on clothing. Symptoms include raised, yellow lesions on the leaves, twigs and, sometimes, on the fruit. In serious cases, defoliation may occur, or the fruit may drop prematurely from the tree. Or, in the worst cases, dieback may occur, which is when the tree dies from the tips of the branches inward. There is no way to treat the disease--infected trees are usually destroyed before it can spread, according to Citrus Canker can be prevented, however, with the systematic application of fungicides containing copper.


This disease originates in the soil, according to the University of Florida. It is caused by a fungus that lives in the soil and thrives in moist, organic material. The disease causes the roots of the tree to rot and is signified by an overall decline in the health of the tree. Other symptoms include bark peeling off the trunk (especially near the ground) and the appearance of wounds, which often ooze resin. There is no way to treat the diseases once it takes hold of the tree. Phytophthora can be prevented, however, by planting citrus trees in very well-draining soil and taking steps to make sure the soil never remains overly wet. Mulching, for example, is not recommended for citrus trees, and watering should only be done early in the day so that the sun can quickly dry the top layer of soil.

Orangedog Caterpillars

This insect pest is the larvae of the swallowtail butterfly, but it is often nicknamed the "orangedog" for its fuzzy brown appearance. Easily visible to the naked eye, this 1- to 2-inch-long caterpillar loves to munch on the leaves of citrus trees. A large infestation of them can defoliate a tree in just a few days. The best way to rid your citrus tree of these pests is to simply pluck them off by hand. If there are too many of them, try spraying the tree with an insecticide labeled safe for use with citrus trees, such as one containing Bacillus thuringiensis.

Keywords: citrus tree diseases, citrus insect pests, problems with citrus

About this Author

April Sanders has been a professional writer since 1998. She has worked as an educator and now writes academic research content for EBSCO Publishing and elementary reading curriculum for Compass Publishing. She holds a Bachelor of Arts in social psychology from the University of Washington and a master's degree in information sciences and technology in education from Mansfield University.