Mango Tree Diseases

Healthy mango fruit can be yours with proper tree maintenance.

There are a few common mango tree diseases in the United States. The diseases, if left unchecked, can infect not only the homeowner's backyard fruit trees, but those of neighboring yards as well. If you're a fan of the luscious tropical mango fruit, the following information will help you identify diseases that may invade your trees.

Common Diseases That Affect Mangos

There are several common mango tree diseases that can decimate a crop of fruit, and in some cases, kill these trees. The following are the most often diagnosed diseases as well as the method of treatment for each case.

Athracnose

One of the most serious diseases is athracnose. It is caused by the Colletotrichum gleosporioides fungus. Symptoms of this disease include dark leaf spots, blossom blight and fruit rot. The spots that appear on the leaves are small and black or brown. These spots can be small dots or as large as a half-inch in diameter in older trees. The spots may appear much larger in younger trees, and entire branches will have leaves that wither and die.

The infection may also appear when the tree is in bloom. The symptoms are brown spots appearing on the flowers, which then turn brown and fall off. Buds are also affected, turning brown, enlarging and then dying off. In regards to the fruit, the fungus infects the skin of the fruit. As it begins to ripen, black spots will appear. The fungus not only causes rotting of the outer skin, but the interior of the fruit as well.

This fungus is spread from spores that live in dead leaves on the ground. Once the tree is infected, the spores are transmitted to other branches via water droplets. During lengthy, rainy springs the disease is readily transmitted throughout entire orchards.

The treatment is two-pronged. First, it is important to remove dead leaves and branches at the end of every growing season. Second, the trees may be treated with a fungicide at several intervals, which include starting at the beginning of the growing period and ending post-harvest.

Verticillium Wilt

Verticillium wilt is caused by the Verticillium albo-atrum fungus that lives in the soil. Mango trees that are planted in areas previously used for growing vegetables, such as tomatoes, appear to be most susceptible. The symptoms of a tree infected with this fungus include leaves on one side of the tree wilting, then turning brown and dying. The leaves usually stay attached to the tree, making this disease somewhat easy to identify. To positively identify this disease, a branch is cut from the tree then a longitudinal incision is made. The inside of a tree infected with verticillium wilt will have a brown appearance due to vascular degeneration inside. Trees with this disease cannot be saved.

Powdery Mildew

Powdery mildew is caused by the Oidium fungus. It appears when there are prolonged periods of cool, dry temperatures. The symptoms of the disease can be identified with the appearance of a white, powdery-like substance on the panicles, new fruit and the undersides of new leaves. This disease can cause premature leaf and fruit drop. Mature leaves that are infected have spots that appear a purplish-brown color. This occurs as the white fungus begins to disappear.

The treatment for this fungus is a fungicide program that begins in early spring and extends to the end of the crop season.

Red Rust

Red rust is caused by a parasitic alga, Cephaleuros spp. One of the symptoms of this disease is the appearance of dozens of tiny, rust-colored spots on the leaves. If left unchecked, the disease can spread from the leaves to the stems and bark of the tree. Red spore masses will thicken these areas and cause cankers, which will eventually have to be removed by pruning.

The treatment for this disease is a program of copper fungicides starting in the spring and applied periodically throughout the growing season. Organic foliar fungicides have not been effective in eliminating this disease.

Managing Your Mango Tree's Health

Most mango tree diseases can be managed by cleaning up dead leaves and branches at the end of the growing season and by periodic applications of fungicides. However, not all diseases can be eliminated entirely because some fungi may remain dormant in the soil for several years or can be spread by neighboring stands of trees. At the first sign of infection, begin a regimen of fungicide applications. If there are no signs of improvement, contact your local Cooperative Extension office or the nursery where you purchased your trees for a correct diagnosis of the disease..

Mango Tree Diseases