Ustilago maydis (DC) Corda syn. Ustilago zeae Ung. Corn Smut,
Cuitlacoche, Huitlacoche. This smut fungus attacks maize or corn causing a bulbous greyish-white fungal growth with a black interior to form on the corn ears, and sometimes a series of grey-black patches on leaves or stems. For farmers all over the world it has been considered a pest, but in Mexico the sweet corn infected with the fungus is a culinary delicacy known as Cuitlacoche or Huitlacoche (the name taken from the ancient Nauhatl). Pseudohyphae and short hyphae with clamp connections are sometimes present. The blastoconidia are irregular, spindle shaped. The teliospores are generated in the corn cob and on maturity are dispersed by wind, they then can overwinter in the soil and infect the next year's growth. For best eating, cuitlacoche should be harvested 16-18 days after infection, once the teliospores are mature. Edible and choice when maturing on corn cobs. Found all over the world, but most easily found in Mexico and some parts of the USA where deliberate infection takes place in order to produce a crop for sale. The images of Cuitlacoche in the edible stage has been lent to me by Jane Levi and Alex Veness.