M__Gorden
Guest
A similar problem occurs when attempting to absolutely prevent the spread of noxious weeds. Combines are not easy machines to clean out. In fact, as a practical matter, I think they are impossible to absolutely clean out. So, the matter boils down to how to prevent contamination. Either the machine be completely disassembled and cleansed or you dedicate machines to specific fields and varieties. The question then is whether or not the need for absolutely eliminating contamination justifies the use of dedicated machines.