Sycamore anthracnose

Natural History
Sycamore anthracnose defoliation
Photo credit: Bugwood.org

Sycamore anthracnose is a disease caused by the fungus Apiognomonia veneta. Anthracnose is a general term that refers to necrosis or dead patches that occur on leaves – and sometimes buds and stems of numerous hardwood species. Sycamore anthracnose affects buds, twigs, shoots and leaves of trees in the genus Platanus. These trees are commonly called sycamores or plane trees.

In early spring, twigs and buds that are infected by spores produced by the fungus that has overwintered in leaf and stem litter die before leaves emerge. Small black fruiting bodies often form on killed tissues and new infections take place on developing shoots. These developing shoots and new leaves often die suddenly as a result. Later in the summer, secondary infections take place on both new and old leaves.

Cool, moist weather in March and April favors the development of the disease. Severely affected trees may be defoliated prematurely and cankers on stems can cause significant dieback.


 

Identifying Characteristics

Identifying the injury: Dead twigs and buds in early spring; shoot dieback beginning in late spring and necrosis (dead patches) on new and old leaves – often beginning along the main veins and midrib, then coalescing into larger lesions during summer. Defoliation may occur and trees may refoliate during warmer and drier weather. Larger branches may die after several years of infection.
Identifying the pathogen: Small black fruiting bodies and microscopic spores on stems and twigs. Also, microscopic spores and fruiting bodies on infected leaves.
Susceptible trees: American sycamore (Platanus occidentalis) in Florida.

 

Images

Click on any thumbnail to see a photo. Use left and right arrows to navigate. Use "esc" to exit the lightbox.

 

Learn More