It looks like these trees have symptoms of sycamore anthracnose. This is a fungal disease that develops in cool, wet weather in the spring. Symptoms may include shoot dieback and brown areas on the leaves that appear primarily along the leaf veins. The symptoms in some years can be severe (depending on the weather), but this disease rarely affects the overall health of mature trees. Once infections occur, there are no control options. (Fungicides are only effective if applied as a preventive measure before the infection would occur.)

As the growing season progresses, new foliage will replace the growth that has been lost to anthracnose, and trees will regain most of their canopy. Practices such as irrigation during long periods of dry weather and avoiding root disturbances can be beneficial to reduce stress on the trees and support their overall health.

Christa