Although citrus and mango trees are not related, they share some similarities. They're both subject to frost and cold damage, though mangos are more frost-tender than citrus and are normally successful only when you grow them in frost-free regions. Both types of trees can be subject to some of the same insect pests and diseases.
Scale insects are hard-bodied suckers that can be hard to get rid of after they are established. Mix one half cup of dishwashing liquid with two cups of canola or other vegetable oil in a blender, and then measure one tablespoon into a spray bottle with one quart of water. Spray it on your tree---it will smother scale insects, aphids, some caterpillars, mites, citrus leaf miners and small grasshoppers, according to the Web site ABC Riverina, from New South Wales, Australia.
Mealybugs, Aphids, Fruit Flies and Mites
Insecticidal soap spray is effective in controlling these types of insects. Yellow sticky traps can help to kill fruit flies in your trees when fruit is beginning to ripen. The California Rare Fruit Growers recommends spraying with a sulfur spray for control of mites.
Bacterial Spot and Bacterial Blast
If your mango tree's leaves become black and distorted and developing fruit becomes disfigured, your tree could be suffering from the disease bacterial spot. The Northern Territory (Australia) Government recommends spraying affected trees with a copper spray. Citrus trees are subject to a similar disease called bacterial blast, according to the University of California at Davis. Its Web site reports that this disease begins as black lesions on the leaves. After the disease encircles the petiole, leaves wither and later drop. Citrus fruits will develop small black spots. UC Davis recommends that using sprays designed for brown rot or septoria might provide help for bacterial blast.
Anthracnose affects both citrus and mango trees. The University of California at Davis reports that this disease manifests itself through dying twigs, leaves that drop prematurely, stain marks on fruit and fruit that decays quickly after harvest. You will see dark spores on leaves and twigs. The California Rare Fruit Growers advise that you can control anthracnose if you spray your tree with a copper spray every other month until flowers open, and then repeat spraying after fruit begins to form.
Powdery mildew is a fungal disease that causes the leaves of citrus and mangoes to become covered with a white or gray fuzzy. It often occurs during foggy or rainy weather, according to the California Rare Fruit Growers. This organization advises that you spray your tree with powdered kelp when flower buds open. Fungicide sprays and sodium bicarbonate can also be effective.