Mango Tree with Fungus on the Trunk

Alga Spot

• Alga spot, also called red rust or green scurf, causes the development of cankers -- open wounds -- on the bark of a mango tree along with a collection of red or rust-colored fungal spores on the stems. The fungus causes those stems to thicken significantly at the infection site. The disease is caused by a parasitic alga of the Cephaleuros species and also produces gray or green leaf spots that eventually turn red with the same fungal affliction.

Verticillium Wilt

• Verticillium wilt is a soil-borne fungus that lives in a dormant state within the earth for as long as 15 years. The fungus Verticillium albo-atrum invades a mango tree through the roots, moving its way up the tree and inhibiting a proper flow of water from reaching all appendages of the specimen. The tree will display signs of water stress throughout the foliage, while the fungus is visible as a discoloration underneath the bark of the trunk and branches.

Wilt Symptoms

• Verticillium wilt is especially easy to diagnose because brown, dead leaves typically remain attached to infected branches rather than dropping away. In addition to a "fried" appearance, the fungus normally only manifests on one side of the tree, leaving healthy branches and leaves on the other side. Verticillium wilt is primarily a problem when vegetables like tomatoes have previously been planted in the same soil. As a precaution, mango trees should not be placed in these environments.

Anthracnose and Powdery Mildew

• Anthracnose does not display on the trunk but is considered the most potentially damaging fungal disease of the mango tree. Caused by the fungus Colletotrichum gleosporioides, anthracnose initially displays as leaf spots on the foliage, then enlarges, killing the fruit and significantly reducing the yield and quality of mangoes produced. The disease can be controlled by application of fungicides.

  The condition known as powdery mildew is caused by another fungus, Oidium, and also can result in the loss of the mango crop.