Abstract: Method of fumigating bulk cereal grains while in storage, comprising the steps of providing a closed empty compartment having internal and external walls in which compartment said cereal grain is to be stored; initially exposing the internal walls of said empty compartment and the space within said compartment to a first fumigant to disinfect the compartment; said first fumigant being providing in sufficient volume to leave a residue film deposit of fumigant on said internal walls; inspecting the external walls of said compartment to ascertain the degree of air-tightness of said empty compartment during said initial fumigation by seeking to detect leaks; repairing any leaks detected during said initial fumigation and inspection; thereafter loading said compartment with bulk cereal grain; and closing said compartment and exposing said grain to a second fumigant to disinfect said bulk cereal grain with said second fumigant as well as with said residue of said first fumigant.