Chemurgy demonstrated its worth during World War II, particularly in alleviating the rubber shortage caused when Japan cut off most of America's supply. Corn was used as raw material in much of the synthetic rubber produced during the war. Various other plants, including guayule and kok-saghyz (Russian dandelion), were investigated as rubber sources. In the American Midwest, school children were encouraged to gather milkweed floss, previously considered a nuisance but now valued for a new role as a filler in military life jackets. A priest in Iowa even made news by urging congregants to grow hemp, whose previous reputation as a drug hazard yielded to military requirements for rope and cordage.