What is anthracnose?

Anthracnose is a fungal infection most commonly seen in sycamores, maples, and oaks throughout Westchester County and the broader Northeast. The disease thrives during cool, wet springs when fungal spores spread through water splash and contact with new foliage.

Symptoms appear as irregular, dark brown to black blotches on leaves, often with a lighter center and a darker border. Infected leaves may curl, wilt, or drop prematurely. On twigs and branches, anthracnose can cause cankers (sunken, dead areas) that persist through winter. Severely affected trees may lose most of their foliage by midsummer, though the damage is usually not fatal to mature trees.

The disease cycle peaks in spring as buds break and leaf tissue becomes susceptible. Wet weather in May and June typically brings the heaviest infection. By mid-summer, when conditions dry out, new growth often emerges healthy. Fall defoliation appears worse some years than others depending on spring moisture.

While anthracnose does not kill established trees, repeated annual infections can weaken branch structure and reduce tree vigor over time. Newly planted or stressed trees are more vulnerable to significant damage. An arborist can evaluate the severity and recommend management options, from sanitation and pruning to fungicide applications in severe cases.