Since numerous species of fungi are capable of transmitting potentially destructive diseases to plants, knowing how to diagnose and treat these fungal diseases is a critical component of protecting health of any plants you grow. Mango trees, for example, are susceptible to a range of fungal diseases; identifying and treating these fungal diseases is crucial not only to protecting the quality and safety of the plant's fruit yield but to protecting the long-term health and life of the plant altogether.
Look at the mango trees to identify symptoms. Each fungal disease of mango trees has its own unique symptoms, and treatment will only be effective to the extent that it is targeted at the specific fungal disease with which your mango tree is infected. Some of the most common symptoms of fungal diseases that infect mango trees include leaf spotting, fruit rotting, lesions on stems and leaves, leaf wilting and yellowing and physical mold growth on different parts of the mango tree's anatomy. Noting which of these symptoms your mangoes have and which they do not is the first step to identifying and treating the disease.
Diagnose the disease based on these symptoms. Anthracnose, for instance, will cause dark-colored spots on leaves that enlarge and eventually coalesce and kill new flower buds. Powdery mildew, as the name implies, is characterized by white, powdery mold growth on all parts of the plant's anatomy. Alga spot is distinguished by gray or green spots that eventually turn rust red. Verticillium wilt can be recognized if one side of the mango tree's foliage wilts and dies while the other side remains normal. These are only the most common fungal diseases of mango; there are several others that each have their own symptoms as well.
Control the disease. Again, this step is highly dependent on the disease in question. If the disease has not progressed to an advanced stage, control can sometimes be achieved by pruning off and discarding the infected parts of a tree's anatomy. Often, however, full control can only be achieved by using a chemical fungicide. Purchase a fungicide that is targeted at the specific disease causing problems for your mango trees and is safe for use on mango trees. Apply it exactly according to the manufacturer's directions. Monitor the tree after applying the fungicide to check for suppression of the disease.
Prevent future infections by exercising preventative disease control measures. Pathogenic fungi can often persist in soil for long periods of time, so if infection reoccurs every growing season, it may be necessary to transplant the mango tree to different soil. If a single disease is a common problem over successive growing seasons, you can apply a preventative fungicide to the mango tree's soil in order to prevent infection over the entire growing season. Also consider replacing your mango trees with more disease-resistant cultivars.