During winter these fungi reside in diseased leaf and stem tissue. In early spring, infectious spores are produced which are carried by rain and wind to newly emerging leaves. Additional spores are produced from recently infected leaf tissue which allows further spread of the disease. Temperature and rainfall are the two key factors which determine severity of anthracnose. Higher or lower average temperature during this period will reduce disease severity.
Frequent rains aid the dispersal of spores and also allow for increased infection.
Most trees are able to withstand infection and push out a new crop of leaves by mid-June. Therefore, the most practical control is to water and fertilize stricken trees to help them recover from severe defoliation. Spraying with fungicides helps reduce the severity of anthracnose but is time-consuming and expensive. Also, by the time injury is apparent, fungicide sprays are usually too late. Thus, spraying is generally not warranted on large, or older established street trees.