Directors of Photography:
Library and Archives Canada.
"States the economic importance to the Candian farmer of weed control and describes the development of butyric weedkillers. The selective action of butyrics, with special reference to Canada Thistle, is explained in animation and demonstrated in laboratory tests with time lapse photography. Field tests at experimental farms are shown and examples of practical application on farms across Canada."
Crawley Films, Free Films: Sources of Free 16mm Sponsored Films in Canada Compiled and Published by Crawley Films (Ottawa: Crawley Films, April 1969): 26.
"The economic importance to the Canadian farmer of weed control."