"Farm Diesel" = Off Highway use diesel, red dye. Same as recreational marine diesel. Until recently had a higher sulfur content. As not as much is sold at the gas station may be stale and already have the diesel bug.
I think that is a generalisation. "Off-road" diesel is perfectly fine, provided the station moves enough to have a fresh supply, which is always the case in a farming community. I have never plugged a filter with off road, however have not been so lucky with marine gas stations. An anti microbial agent should be added no matter what the source, as the algae could already be growing in your tank.