By STEVE BINDER
URBANA, Ill. — As the southern Illinois community of Collinsville prepares for its 24th annual International Horseradish Festival later this month, researchers continue work they believe will help growers eliminate a longstanding fungus problem that can discolor horseradish roots.
Mohammad Babadoost, a crop sciences professor at the University of Illinois, has been working on the issue since he first arrived at the school in 1999. At that time, he was told growers in southwestern Illinois were seeing yield declines because of the discoloring.
The region centered around Collinsville, in Madison and St. Clair counties, grows the most horseradish in the United States. Roughly 60 percent of the world’s supply comes from this region, commonly referred to as The Bottoms, where glaciers helped create the Mississippi River and left soil with a high level of potash.
Babadoost notes the soil conditions, coupled with longer summer growing seasons and cold winters, are ideal for growing the root that is part of the mustard family. The festival was already 11 years old when he and his team dove into the discoloration issue, something he called complex and time-consuming to identify.
First, roots that aren’t near white aren’t saleable. According the USDA, about 25 million pounds of horseradish root was processed last year, into about 6 million gallons of prepared horseradish.
“If the roots are discolored, they are not accepted for processing,” Babadoost said. “What we’ve learned so far is that growers can take some extra steps to prevent this from happening.”
Initially, researchers believed the discoloration problem was linked to one fungus in particular, Verticillium dahlia, but Babadoost wasn’t convinced a single fungus was the lone culprit.
“I realized that it was a serious problem, and I thought it could be a complex problem rather than a single-pathogen/single-disease problem,” he explained.
By 2004, his team identified three different fungi that contributed to the problem. “But I was still not completely convinced that that was the end of the story,” he said.
He explained they continue to see a lot of root rot that did not appear to be caused by the identified pathogens. A short time later Babadoost and his team linked an additional fungi, Fusarium commune, to the discoloration problem and to combat it, the professor said growers can add two steps to their growing process.
Infected roots early in the spring can be cleaned in hot water and replanted, and then certain fungicides can protect the roots from infection for about three months.
“If these two techniques are combined, by the end of the season in the fall the roots are either not infected or discoloration from infection is negligible, so you can sell the roots,” he said.
The research is detailed in the April 2013 issue of Plant Disease.
This year’s festival in Collinsville, which proclaims itself the “Horseradish Capital of the World,” runs from May 31-June 2 in Woodland Park. It will feature live music, food booths and numerous games and contests such as root golf, root toss, root sacking, recipe contests, the Horseradish Root Derby and the Little Miss Horseradish Festival Pageant. Find details online at www.horseradish festival.net