en.wikipedia.org/wiki/Stem_rust

"The stem, black or cereal rusts are caused by the fungus Puccinia graminis and are a significant disease affecting cereal crops. An epidemic of stem rust on wheat caused by race Ug99 is currently spreading across Africa, Asia and most recently into Middle East and is causing major concern and an increase of food riots and civil unrest, notably in West and Central Africa among the worst-hit countries."

en.wikipedia.org/wiki/Stem...ponization

"The United States produced wheat stem rust and rye stem rust as part of its biological weapons program, which was active from 1943-1969.[6] Wheat and rye stem rust was produced from 1951-1957 at Fort Detrick then shipped to Edgewood Arsenal where it was classified, dried and stored.[7] Again, from 1962-1969 wheat stem rust spores were produced and shipped to Rocky Mountain Arsenal where they too were classified, dried and stored.[7] These anti-agriculture biological agents were tested at least 31 times by the U.S. military."