A southern Mallee farmer believes it will be physically impossible to move the district's grain harvest by road if the region produces a good crop this season.

The Wimmera Regional Transport Group has been told that centres, including Hopetoun and Rainbow, will not be serviced by Graincorp's contracted rail freight services.

The group says it means grain from a significant section of the Wimmera Mallee's farms will need to travel long distances in trucks by road.

Rainbow district grain grower Bob Schilling says he does not think the region's roads will cope if rail services are not available.

"Well I think it's a very great concern, not only for us getting rid of grain, I just can't understand how they're going to shift it all on the roads," Mr Schilling said.

"Where we go from here, I think we all just have to stand up and make a lot of noise and get through to politicians that it's just not a feasible option to not have rail."