Flag smut of wheat

The flag smut fungus, U. agropyri, is a basidiomycete. It produces basidiospores and teliospores. This pathogen is found globally, but is most problematic in Australia and India.

Urocystis agropyri only infects wheat (Tritiicum aestivum L.) Relatives of U. agropyri infect other grasses and are frequently identified as the causal organism of flag smut on wheat, but there is debate still as to whether they are the same organism or different strains.

Flag smut is a systemic disease that starts in young tissues. Early symptoms include "leprous" spots and bending or twisting of coleoptiles.Older plant leaves have white striations that eventually turn silvery gray, which is evidence of the pathogen's impending sporulation.  Additionally, infected plants may have stunted growth, increased leaf production, sterile seeds, and failure to produce heads or have successful leaf expansion.