Also known as corn smut, ustilago maydis is a pathogenic fungus that causes a disease in corn. It appears as a scorched or burned appearance on the corn. Though considered a pest and destroyed by farmers in many countries, the fungus is used in Latin American cooking as well as in herbal remedies.
The fungus feeds off the corn plant, thereby decreasing the crop's overall yield. It can feed off any part of the crop, though it often enters through the plant's ovaries. When this occurs, the cob kernels are replaced with large, mushroom-like tumors, or galls. These galls, filled with blue-black spores, are what gives the corn a bruised look. The structures can also appear on the plant's tassels, stalks, buds, and leaves.
Considered a delicacy in Latin American countries, corn containing ustilago maydis is often sold at a higher price than unaffected crops. Galls are harvested while they are young to retain their moisture. This is typically two to three weeks after an ear of corn has contracted the infection.
When prepared as a food, U. maydis is typically used as a filling in tortilla-based meals, such as quesadillas. They possess a flavor similar to that of sweet, earthy mushrooms, making them a popular appetizer and soup ingredient as well. U. maydis is rich in nutrients and contains high levels of vitamins, oleic acids, linoleic acids, and essential amino acids. It is also a source of protein and carbohydrates.
In the American Southwest, Native tribes, such as the Zuni tribe, used ustilago maydis to induce labor. They referred to the fungus as the symbol of the generation of life. Most tribes, however, simply used it in cooking.
A member of the Basidiomycetes fungi family, ustilago maydis is also known as huitlacoche, a name given to the fungus by the Aztecs, in Latin America. This translates to "raven's excrement." Latin American farmers spread the infestation purposefully when it appears for maximum usability and profits.
Many farmers from other countries destroy infected crops, though European and American governments and chefs have attempted to encourage its growth and sale. In order to keep up with demand for the food, farms in Florida and Pennsylvania have been permitted to infect their crops for its production. There is little farmers can do to prevent the fungus from infecting crops. Some use corn containing ustilago maydis as corn silage to feed their livestock.