• A healthy citrus tree will provide fruit for many years.orange sur un oranger image by MONIQUE POUZET from Fotolia.com
  
  Mango trees, like citrus trees such as lemon, orange and lime trees, require a frost-free growing climate. They are susceptible to multiple pests and diseases that can inhibit plant growth, ruin fruit, and even kill whole trees. Disease and pests of mangoes and oranges include fungus, parasites and viruses as well as insect infestations.
  
  

Citrus Diseases

• Citrus trees are vulnerable to three types of diseases: fungal, parasitic and viral. Fungal diseases such as Phytophthora foot rot and Rio Grande gummosis are caused by parasites in the soil and can be prevented by using resistant root-stock and planting the trees in well drained soil. Other fungal diseases such as Hendersonula branch wilt and brown heartwood rot of lemons are caused by fungus invading trees through wounds and can be controlled by pruning the affected areas before they spread. Blue and green fruit mold and alternaria fruit rot are fungi that affect the fruit and can be controlled by using sanitary practices when picking fruit and maintaining well fertilized trees. Parasitic diseases of citrus include psoriasis and the citrus tristeza virus. Psoriasis in citrus appears as brown scales and flakes on the fruit and can only be controlled by eradication of affected trees. Citrus tristeza virus (CTV) causes reduced fruit size, yellowing of the leaves and eventual girdling of the tree that will kill it. CTV is controlled through quarantine and eradication of infected trees.
  
  

Citrus Pests

• There are five major pests of citrus trees; they cause damage ranging from minor cosmetic damage to tree death. Orange dog caterpillars affect the leaves of young fruit trees by stripping them. Older trees can withstand the damage, but the caterpillars are easily controlled by manually destroying caterpillars and eggs. Aphids can attack citrus trees and spread the citrus tristeza virus. They can be controlled by the use of parasitic wasps, lady beetles and lacewings. Cottony-cushion scale feeds on citrus trees but can be controlled by pruning affected branches and using vedalia beetles. Citrus thrips cause cosmetic damage to the skin of citrus fruits but are considered beneficial insects because they feed on spider mites. Citrus mites leave yellow spots on the leaves and sticky webbing on the backs of leaves. Mites are attracted to trees that are water stressed, so proper irrigation can mitigate the damage.
  
  

Mango Diseases

• Mangoes are mainly affected by fungal diseases and parasites. The worst mango disease is a fungal disease called anthracnose, which causes blights of flowers and fruit rot, which reduces yield. Anthracnose is controlled by planting resistant cultivars and the use of fungicidal sprays. Powdery mildew is a fungus disease that can prevent fruit from setting on the tree. White growth on the bottom of the leaves causes the leaves to drop and can be controlled with fungicides. Verticillium wilt is caused by a soil-borne fungus that inhabits soil that was previously planted in vegetables, particularly tomatoes. There is no treatment, but it can be avoided by planting mangoes in soil that has never been planted with vegetables. Mangoes are also susceptible to parasitic alga. Alga causes leaf spots and cankers on the bark and can only be controlled with copper based fungicides.
  
  

Mango Pests

• Mangoes are vulnerable to mites, thrips and scale similar to those that affect citrus trees as well as ambrosia beetles. Mites cause leaf drop, reducing photosynthesis and fruit yields. Mangoes are affected by three types of thrips which feed on blossoms and prevent fruit set. Scale insects feed on leaves but are rarely found in enough numbers to reduce fruit yield. All three of these pests are prevented by the use of insecticides and beneficial insects. Ambrosia beetles attack the stems and branches of previously weakened trees. Major infestation can lead to pests in otherwise healthy trees. Ambrosia beetles are controlled with pesticides.