Sycamore leaves found on the ground

Sycamore leaves found on the ground

Observation - Sycamore leaves found on the ground - UK and Ireland. Description: The green patches on the Sycamore leaves are reminiscent of the effect of cytokins. I wonder if they could be due to a fungus. I would be grateful for any suggestions as to their cause. It is possible that a fungus is damaging the leaves locally, delayin

The green patches on the Sycamore leaves are reminiscent of the effect of cytokins. I wonder if they could be due to a fungus.
I would be grateful for any suggestions as to their cause. It is possible that a fungus is damaging the leaves locally, delaying the natural senescence-induced chlorophyll loss. I have seen this elsewhere in previous years so it is not uncommon.