It certainly is unusual and striking. People
unfamiliar with your country would need to see more of the plant to give a
definitive answer, but there are obvious regions of dead tissue round some teeth
on the leaf’s edges, in a pattern suggesting that the problem is not a typical
plant disease attacking the leaf. Viruses tend to produce vaguer patches of
yellowing (chlorosis), and bacteria often produce spots or dead patches that do
not follow venation patterns. The fact
that the chlorosis attacks the *veins*, leaving healthy islands of chlorophyll surrounded by paler green areas, is
the opposite of what one expects from a deficiency of say, iron, manganese, or
zinc in the soil. It all suggests that the leaf first grew well, then suddenly
encountered a non-specific deficiency that progressed from the roots outwards towards
healthily established tissue.
This appearance would be consistent with
the plant being attacked by stem damage or stem rot, root rot or drowning, or
some similar stoppage of food supplies from the roots, such as eelworm. If you found it recently, I don't suppose it could be an autumn leaf. I
cannot be certain, but to me it does not look much like pollution
damage.
