Minnesota detects soybean disease without treatment

Red crown rot, a fungal disease that burrows into the soil, rots soybean roots and destroys part of the bean’s leaf tissue, has been found in Minnesota. There is no cure for it.

When a Rock County farmer sent samples for testing in September, he was puzzled, said Dean Malvec, an extension disease researcher at the University of Minnesota.

“At first, we were wondering if this was really ‘red crown rot,'” Malvik said. “Because it has not been discovered anywhere near this location.”

Red crown rot was previously discovered in Missouri last year. How it made its way north without being detected in Iowa or other neighboring states remains a mystery.

“It’s a widespread concern,” Malvec said.

But how the disease spreads remains a question mark. It was first found more than fifty years ago in North Carolina and has since spread from state to state, eventually landing in the Midwest in 2018 after rot was discovered in Illinois.

Since red crown rot is a fungus found in the soil, high-speed winds likely played a role in spreading the disease.

“We don’t really know how the disease spreads,” Malvik said. “That’s a real wide-open question.”

Until that question is answered, Malvik said we won’t know where the fungus might be or how widespread it actually is.

“There are a lot of questions here about (red crown rot), how important and devastating it is in Minnesota,” Malvec said. “It might be really important, or maybe it’s not so important.”

While Malvik is concerned about the presence of mold in the state, he said there is no cause for concern.

Because the disease was discovered in the fall, his team can use the winter as an opportunity to further study the mold. Most soybeans won’t be planted in the cold anyway, which gives them time to prepare for the spring planting season.

“That will be one of the things we will do: help people understand what this disease is,” Malvec said. “The follow-up next summer will be a much larger effort to look for it, explore it, survey it and try to pinpoint where else it could occur.”