It has been said that these trees are infected with Anthracnose fungi.
Anthracnose fungi occur primarily on leaves and twigs. On deciduous trees these fungi overwinter in infected twigs. In spring many microscopic spores are produced and spread by splashing rain or sprinkler water to new growth where they germinate; the fungus enters the leaves and newly expanded twigs. If moist conditions prevail, a successive generation of spores is produced in the infected parts of new leaves. On evergreen species such as Chinese elm, the fungus can occur year-round on leaves and twigs, but on most deciduous trees the progress of the disease slows and becomes negligible during the hot dry summer.
These are London Plane Sycamores. One particular London Plane variety (Yarwood) is more susceptible to disease than others (Bloodgood, Columbia, Liberty).
Maybe the city got these trees on sale?
Was down at Pier A yesterday, and noticed a many of the trees embedded beneath the sidewalk bricks had become brown and the leaves had already begun falling off.
I cannot recall if this happens every year, due to the kind of trees they are (any Arboriculture specialists out there?), or if the trees just cannot handle this type of installation.
Perhaps it’s a sign that we’re going to have a bad winter this year?