The reason your tree has black spots on its leaves is due to a fungal disease called Diplocarpon rosae. The fungus causes the tan color in the leaf tissue and overwinters on the affected leaves. In times of high humidity, the fungal spores are splashed onto newly growing leaves, infecting them. The fungus causes the tans in the leaf tissue, which is similar to a drop of tar. The leaves are also susceptible to new twig growth, but it is unlikely to kill the tree. However, you should get rid of infected leaves if you suspect that they have been infected by the disease if you are unsure of the cause.
Leaf spots can be caused by air pollution, insects, or bacteria. However, most of the time, they are caused by pathogenic fungi that destroy the leaf tissue. The fungi cause pinhead-sized spots that can be very difficult to detect. Infected leaves will have black or brown, necrotic areas, and reddish borders. The disease can also result in partial defoliation.
Several causes of leaf spots can be found on maple trees. These include environmental damage, insects, and fungi. The most common causes of leaf spots are rust, and decay. Pests can also damage the leaves. These fungi can kill the leaf tissue, which results in black spots. Often, you can treat your tree with fungicide sprays in early spring to prevent the disease from occurring again.