Mango trees (Mangifera indica), large ornamental evergreen trees with sweet, savory and juicy fruits, grow as tall as 45 feet and 50 feet wide. The trees thrive in U.S. Department of Agriculture plant hardiness zones 10 through 11. Under normal conditions, this full-sun tree has elongated leaves that are purple as they emerge but turn deep green as they mature. If you notice dry, brown spots on your mango leaves, it may be a sign of various health problems.
Anthracnose is a fungal disease that affects mango trees, causing dry spots that are brown to black in color on the leaves. These spots develop first on new leaves, and eventually extend to older leaves. Spots may also be present on mango flowers and even the fruits. The spots are visible through the entire leaf tissue, on both the upper and lower leaf surfaces. As anthracnose progresses, the leaves begin to curl and wilt, and the stems of the tree begin to die back. Eventually the leaves, flowers and fruits become so deformed that they drop prematurely.
Bacterial Leaf Spot
Bacterial leaf spot on a mango tree starts as wet brown spots on the surface of the leaves. These spots resemble water-soaked blisters and are accompanied by small holes in the leaves. Eventually, the brown spots dry out and harden to a wax-like texture. Bacterial leaf spot is caused by the pathogen Xanthomonas campestris. If allowed to progress, this disease causes dead, dropping leaves on your mango tree.
If you notice brown spots on the undersides of your leaves and yellow spots on the upper sides, leaf blight is the likely culprit. Leaf blight commonly starts on older growth and mature leaves of mango trees. As the disease progresses, the spots increase in size and number, and the yellow spots on the upper leaves turn pale or white. Leaf blight also results in dying, dead and dropping leaves in mango trees.
Problems in the soil extend to problems with your mango tree leaves, such as dry brown spots. Such problems include too much nitrogen or excessive salts in the soil. Both problems come as a result of over-fertilization. Fertilizers increase the amount of salt in the soil and raise the nitrogen levels. Excessive amounts of these elements cause leaf burn in your mango tree, and leaves develop dry, brown spots of patches. If the leaf burn is severe, the leave may die and drop from the tree.
Cultural Care and Treatment
The best way to prevent diseases that cause dry, brown spots, wilting and leaf drop on your mango tree is to provide the best growing conditions and care. Proper cultural care improves the tree’s health and vigor, making it more resistant to common pathogens and diseases. A mango tree requires full sun and fertile, well-draining soil. Stick to a regular schedule of pruning. Always be sure to remove and clean up fallen, dead or diseased branches and leaves to prevent fungal pathogens from overwintering in leaf debris. Fertilize regularly with a slow-release fertilizer so the tree is not exposed to heavy salts or nitrogen too rapidly. Fungicides are only recommended if proper cultural care is practiced but your tree till suffers from brown spots caused by fungal pathogens -- fungicides over an extended period of time can harm the fruit quality. A copper-based fungicide sprayed once a week, prior to flowering, is helpful for protecting old and new leaf tissue from fungal diseases. Follow all product label instructions.
- University of Florida IFAS Extension: Mangifera indica, Mango
- University of Florida IFAS Extension: FAQs -- Tropical Fruits
- Miami Herald- Plant Clinic: Mango Tree Has a Fungal Disease
- Government of Sindh Agriculture Department: Diseases of Mango & Their Control
- The American Phytopathological Society: Bacterial Leaf Spot on Mango
- Photo Credit John Foxx/Stockbyte/Getty Images