In most cases, healthy trees quickly recover from anthracnose infections with little damage to their long-term health. Many different species of fungi cause anthracnose diseases. All cause some kind of leaf spot or leaf blight, and premature leaf drop commonly results from heavy infections. Some anthracnose diseases also cause twig dieback and shoot blight. Although symptoms observed on different tree species may be similar, the various anthracnose pathogens are host specific, meaning, for example, the fungus that causes anthracnose in sycamores does not infect and cause anthracnose in ash.
Weather plays an important role in promoting the development and spread of anthracnose.
These diseases are generally more severe when the weather is cool and wet. Symptoms usually appear in the early spring and intensify in late spring and early summer if weather conditions remain favorable for fungal growth and dispersal. Anthracnose is the most important disease of sycamores in Nebraska. It causes twig canker and dieback, leaf and shoot blight, and often substantial defoliation. The fungus that causes sycamore anthracnose, Apiognomonia veneta, overwinters in twigs on the tree and becomes active whenever temperatures permit its growth.