Syntax for eSearch widget

I have a joined field I would like to reference in the easearch widget. I have a table joined to my GIS layer from a database in another instance. The join exists within the map. The field in the rest endpoint is called :

maximo_production."EARTH\GIS".%GIS_NurseryFlat.nORth_itemnum

How do I add this given it has quotes within it and a \?