By girdling you mean, tunneling or chewing. Sorry not familiar with the term girdling.
If on the trees it is in fact a fungal disorder, where would it have come from and what should we do to treat them to prevent losing them altogether?
We had our trees trimmed back last year but equipment was sanitized to prevent spreading anything and the trees that had some issues with dead leaves/branches were put off to be addressed last. Just in case they were sick and to avoid the possible spread of fungus if they were in fact infected.
Sorry to ask so many questions I just want to understand and try to keep from losing any more moving forward.