May. The spores are blown and splashed to the buds and young leaves and, with favorable moisture conditions, penetrate and infect the swelling buds and unfolding leaves. Long rainy periods help the fungus to spread rapidly. Control Disease control measures for different trees vary slightly because the period of infection is different depending on the fungal species involved. If fungicides are used, sprays must be applied on a preventative basis, beginning before infection takes place. Spraying large trees for many anthracnose diseases may be impractical and unnecessary, especially in dry springs.
Sanitation is important in reducing the amount of fungal inoculum available for new infections.
Two trees on right showing symptoms of sycamore anthracnose compared to tree injected with Arbotect 20-S fungicide on left. Leaves may be shredded and composted or burned. Prune out and burn or bury dead twigs and small branches. Prune to thin the crown. Thinning will improve air movement and promote faster drying of the leaves.