Why Is My Sycamore Tree Losing New Leaves Fast?

Anthracnose

• Anthracnose is a serious disease of sycamores, leading to the tree losing new leaves fast. A variety of fungal pathogens cause leaves to develop dark spots and sunken lesions. Unfolding, young leaves are the first to display symptoms of infection, eventually turning brown, curling and falling to the ground. The disease -- which is often confused with frost damage -- then turns its attention to older leaves, causing them to prematurely drop to the earth.

Weather

• Anthracnose initially becomes apparent in the spring, spurred on by cool, wet weather that enables the fungus to more easily spread throughout the leaves of a sycamore and other trees. If the temperature consistently remains below 55 degrees Fahrenheit for the two-week period following the first emergence of leaves, the anthracnose problem is likely to be severe. Should the average temperature climb above 60 degrees Fahrenheit, then anthracnose infection throughout the tree is unlikely.

Cankers

• Anthracnose cankers -- an open wound -- will develop on the twigs and branches of infected sycamores, usually near the base of a clump of diseased leaves. The spring after infection, these cankers become toxic and begin spewing fungal spores throughout the wind, reinfecting both the afflicted tree and others nearby. Large branches will also be injured by the canker as black fruiting bodies of the fungus appear within the wood, often killing the large appendages.

Control

• Fallen leaves and twigs should be gathered and destroyed as they will produce reinfection spores the following spring. Infected twigs and branches should also be pruned away and destroyed, with cankers completely cut out of all branches, leaving nothing behind but healthy wood. Sycamores known to be infected should be watered during snowless periods of winter and fertilized in the spring. Fungicidal sprays can be applied in the spring as soon as leaf buds begin to show.