From your screenshot you are trying to save the changes in the Route Layer whereas you need to save the setting for industry in the sessions layer IIRC
I think that we might actually have wheat growing right outside our house in the front yard, thanks to all of the squirrels out here in this wooded environment of ours who like to bury corn and likely bird seed as well (which might be what the probable wheat came from). We have actually had several corn stalks growing around here thanks to the squirrels in the somewhat recent past, including one little stalk that even grew a little corn cob.