Apparently, there’s a lot of infested corn that has the potential to be turned into a cash crop, according to a 2012 Purdue University Extension publication. With 83.9 million bushels of corn crops lost to “common smut” or Ustilago maydis in 2012 in the United States’ 22 highest corn-producing states and the province of Ontario, there may exist an untapped source of food for restauranteurs and consumers.
According to the University of Illinois Department of Crop Science, corn smut that’s wild or cultivated is better known in the food world by the name of Aztec origins, huitlacoche. It describes the edible form of corn that is infected with common or boil smut.
Mycologia journal notes that U. maydis cultivation is becoming more attractive due to Americans’ greater acceptance of this as a trendy food item. With the mushroom industry’s production figures growing by 20 percent annually over the past 15 years or so, figures from a 2003 study in Mycologia mentioned huitlacoche retailers commanding as much as $40 per kilogram online.
With restaurants including it on their menus, what potential do New England, New York and Pennsylvania have for producing this harvestable and edible form of corn smut?
The first step in determining if corn smut can be an unintended source of revenue is understanding how much it naturally occurs. Alyssa Collins, Ph.D., director of the Southeast Agricultural Research & Extension Center at Penn State University, says it’s commonly found in corn fields.
“Most cornfields will have some small level of corn smut. If you were to walk up and down a cornfield and go to every row, you would probably find a little bit of it in almost any field, (but) probably less than 1 percent,” Collins said. “It depends on the timing of when that corn got in the ground, and how long a period it’s going to be out there and when it hits. But it’s not unusual to find a little bit of it.”
H. Grant Troop, executive director of The Pennsylvania Corn Growers Association, noted the first way to determine crop efficacy is by the type of corn grown. In Troop’s experience, corn smut is found more often in sweet corn, not corn varieties grown for animal feed.
When it comes to cultivated corn smut crops to make huitlacoche, however, Collins cited a study in Mycologia that demonstrated field corn was more efficient than sweet corn in producing huitlacoche. The study found that when the large-eared field corn received a U. maydis inoculation, after five days of silk production, it produced the highest yield of huitlacoche 16 days after the injection.
Based upon research information from a 2009 publication from Mary Ann Hansen, Extension Plant Pathologist, Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, there’s been research into determining which varieties are more and which are less susceptible to corn smut.
Virginia Tech experts noted that though hybrid varieties of corn can reduce the tendency of corn smut infestation, there are still differences in susceptibility and resistance within sweet corn varieties.
Growers not looking to encourage corn smut infection may seek varieties that have a greater resistance, including Argent, Silver King and Silver Prince and Seneca varieties (such as Snow Prince, Sugar Prince and Sensation). Varieties more prone to corn smut infection include Spring Gold, Duet, Golden Beauty and Country Gentleman Hybrid. Steve Verrill of Verrill Farm in Concord, Massachusetts also mentioned the Silver Queen variety as susceptible to corn smut.
Another factor in corn smut cultivation is the likelihood of corn being infected. Collins explained how corn smut infection generally occurs in fields of corn.
“It’s usually pretty random, and that’s because the fungus itself is a [type of] fungus that survives in corn residue, like a lot of the fungi we deal with,” Collins said. “So, it overwinters in corn residue in fields, and in the spring and summer, when the environmental conditions are conducive for it, it can start sporulating. Then it can blow around and infect what is there to be infected.”
During the normal reproduction process silks grow and wait for the tassel above to start releasing pollen that will eventually move down to the silk – a tube-like structure that eventually forms the corn kernel. However, Collins explained that if there’s corn smut in the area, which is often airborne, it can take the place of pollen that would normally fertilize the silk and instead result in corn smut. Since this process varies and is impacted by weather, it can significantly impact how corn forms.
Weather and reproduction
Collins explained how extreme dry weather and wet weather can impact the creation of healthy corn, increasing the possibility for more corn smut infection.
“It can go both ways. That’s mostly because the weather’s impact on the silk and the pollination are the key factor. If the silk is formed on the corn, and it’s a long time before they get pollinated by actual corn pollen, that’s a longer window for the fungus to get in. In dry periods – hot dry periods, – where the silking and the pollen shed don’t match up, there’s a long period of time for the fungus to get in,” Collins said. “The same can be said if silking or pollination are thrown out of whack by a cool, wet period. So, if you don’t have perfect conditions right around silking, anything that gets in the way of good pollination is going to open the door to more fungus being able to get in.”
Periods of excessive heat and dryness can reduce the average timeframe of 5 to 8 days, along with negatively impacting the pollen’s virility when making contact with corn silk, as the University of Delaware Cooperative Extension explained.
Similarly, the University of Delaware found that periods of high humidity can impact the pollination window. When tassels remain moist through excess humidity or dew, pollen doesn’t naturally migrate to the silk. Combined with the university’s finding that above average amounts of silk are produced during periods of excess moisture, it will either go unpollinated, or if corn smut fungus is present, an infection may result.
Verrill noted his experience with corn smut, especially one corn variety where corn smut was prevalent.
“I used to find it fairly common when we were growing a lot of white varieties, and more specifically Silver Queen. [During] humid, moist times, it seemed to be more prevalent. So it seems to need a certain variety of corn and damp weather.”
Harvesting and sales
When it comes to a naturally occurring corn smut infection, one important consideration is how the crop should be tended. Collins noted that because it’s not a traditional consumer or livestock crop, the need for insecticide use may be less. However, there will be a greater need to monitor the crop to ensure harvest occurs at the right time.
When addressing harvesting, Troop mentioned that it’s akin to foraging for mushrooms in the forest, and explained how to visually identify and handle naturally occurring corn smut infected corn.
“You want to harvest that smut ball when it’s in a wet, moist, sort of pasty consistency. If you wait too long that thing will dry out and become like a puff ball. Just a ball of dry, powdery puff that when you touch it, it falls apart and the spores go flying in the air. It requires pretty timely harvest,” Troop said. “The product itself, once it’s harvested, is highly perishable so you have to store it correctly and get it processed to be used.”
While natural infections follow a similar timeframe, Collins highlighted how growers have more control over cultivated huitlacoche. “When researchers were doing artificial inoculation, they developed a saleable product after about 15 days,” Collins said. Without continual monitoring of naturally infected corn crops, there’s no way to determine the initial date of infection.
In the case of researchers, Collins noted after introducing the corn with the corn smut fungus, they could reliably harvest the infected corn after 15 days to reach it at its peak of infection. However, if the researchers waited even a day longer, the chances of it spoiling became evident.
“If they went over 15 days, they no longer had a product they could use,” because of the pericarp membrane around it, according to Collins. “The pericarp splits, and all the spores start coming out, and at that point, you can’t use it anymore, because it’s just kind of gross, and there are spores all over.”
Since it can spoil easily, Collins recommended “plucking off the galls and freezing them.” While this may give the same quality as fresh huitlacoche, she believes chefs prefer suppliers who can give them a more consistent stock of it, despite the difference compared with fresh product.
While there are many considerations for growing and harvesting corn smut or huitlacoche, understanding the factors that contribute to maximum growth is a good first step in weighing options to harvest edible corn smut for eventual sale to commercial and consumer buyers.