Corn Smut: A Reputation Redeemed

Corn smut, a fungus, is a delicacy growing in popularity.
Corn smut, a fungus, is a delicacy growing in popularity. (By T.a. Zitter)
By Barbara Damrosch
Special to The Washington Post
Thursday, February 15, 2007

Here's the word: Silver Queen, that old favorite sweet corn variety, has a reputation for smut. Not the lurid kind. The kind that erupts from an ear of corn in a large, bulbous mass. It is a parasitic fungus that affects other parts of the plant as well, and most anyone who grows corn has made its acquaintance.

Corn smut, or common smut as it is sometimes called to distinguish it from a stringier corn blight called head smut, is spectacular in action. Individual kernels swell to many times their normal size, taking on a silvery-gray color. Darker on the inside, they eventually break open, shedding multitudes of tiny, sooty bodies called teliospores. These take up residence in the soil, often for years, and infect subsequent crops. For home gardeners, smut is rarely more than a nuisance; for farmers, it can cause economic loss, and at one time the U.S. Department of Agriculture made great efforts to eradicate it. Modern corn hybrids are less susceptible, so you most often find it on open-pollinated ones such as poor old Silver Queen.

Such a slip of the tiara normally might be enough to take a variety out of circulation, even one so notable that other sweet, white-kerneled corns are sometimes marketed under its name. But in recent years the story has taken an odd twist. Enthusiasm for authentic Mexican food has led American chefs to experiment with some of the more esoteric south-of-the-border ingredients, and one of them, called huitlacoche ("weet-la-KO-chay"), is corn smut.

In Mexico's central highlands, when the rains come, corn growers search their fields eagerly for ears infected with the fungus, a favored delicacy since pre-Columbian times. (It is a traditional food in some Native North American tribes as well.) Sometimes spelled cuitlacoche, it lends an earthy, mushroomy, corny flavor to tortilla fillings, soups and other dishes. Farmers plant particular varieties that attract it -- largely field corns, since sweet corn is less common in Mexico. The whole ears, displayed proudly at markets in all their grotesquerie, fetch a much better price than that of healthy corn.

Eager to get in on this, some American farmers now use new methods of producing huitlacoche galls on corn, spurred on by government and university research. Ironically, the most successful experiment was originally anti-smut. Jerald Pataky at the University of Illinois, in an effort to screen corn varieties for smut resistance, developed effective ways of inoculating corn with the disease, achieved at critical moments during the pollination period.

That proved a good method for growing smut on purpose. It's all a bit too high-tech for the average gardener, but it would be fun to try making a slurry of mature smut spores and water, then squirting it into the young silks with a big syringe or squeeze bottle. You could also try the Aztec trick of scraping the plants at ground level in rainy weather and rubbing the galls on the wounds.

The Virginia Cooperative Extension Service offers a short list of varieties most likely to lure the smut fairy -- Duet, Country Gentleman and Golden Beauty, in addition to Silver Queen. Simpler yet, offer to remove any smut that appears in friends' corn patches -- a good deed that helps stop its spread. Post notices in places where gardeners hang out, avoiding coy euphemisms such as "maize mushroom" and "Mexican truffle." "Smut Wanted" will get their attention.

Rick Bayless, author and chef of Topolobampo in Chicago, gave me some good advice about harvesting huitlacoche. (His is grown for him by his former managing chef, Tracy Vowell.) "Pick it when it feels like a pear starting to ripen, when there's a little give to it. Too firm and it will be bitter. Too late, when the thin skin of the gall breaks if you rub it, and it will taste really muddy."

His favorite recipe for a filling involves browning onions and garlic in vegetable oil, adding chopped peppers and tomatoes, cooking them down, then adding huitlacoche and cooking it down some more. For seasoning, he favors the "big, bold flavor of epazote." He also combines huitlacoche with roasted root vegetable such as parsnips, carrots and rutabagas. In Mexico City, he notes, chefs use it in a sauce with roasted poblano peppers and cream.

I've made a great huitlacoche soup with peppers, chicken broth, onions, garlic, Tabasco and both sweet and sour cream. Winter is not the time to cook with huitlacoche unless you've frozen some. What's available in cans is a disappointment. Best to wait for the real thing. Meanwhile, this is a great time to order a packet of Silver Queen.

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