"If we were attacked with nuclear weapons (atomic or hydrogen bombs), you, the American farmer, would be counted on to supply the food and fiber needed to keep the economy going. One of the problems you might face in doing this important job is radioactive fallout. This bulletin contains the recommendations of scientists, engineers, public health officials, Civil Defense authorities, and other specialists. You may not find here all the information that you would like to have on protection against fallout. Study of the effect of radioactive fallout on agriculture is a continuing project. Some of the recommendations in this bulletin may have to be changed in the light of future research. In the event of enemy attack, first provide for your own safety and that of your family and neighbors. To do this, you may initially have to ignore your livestock, your crops, and your land. Your best protection from fallout is to remain indoors, preferably in a basement or cellar, and to avoid contact with contaminated objects. When in doubt, seek shelter. Authorities will make every effort to let you know when it is safe to come out of shelter."
Farmers' Bulletin No. 2107
FEMA Learning Resource Center: http://www.lrc.fema.gov/