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New potato disease found in North Dakota, Minnesota fields

The disease, called “rubbery rot,” was seen in North Dakota and Minnesota this summer and was found in Wisconsin in 2019, said Gary Secor, North Dakota State University Extension plant pathologist.

A man wearing a green polo shirt and blue jeans holds a brown clipboard in his right hand and a black microphone in his left.
Gary Secor, North Dakota State University Extension plant pathologist, talked about potato diseases at Northern Plains Potato Growers Association's annual field day held Aug. 25, 2022, at Hoverson Farms near Larimore, North Dakota.
Ann Bailey / Agweek
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LARIMORE, N.D. — The 2022 growing season has been mostly disease-free for potatoes, but farmers got a heads-up during a research session about a potentially damaging fungus that showed up in the Northern Plains this year.

The disease, called “rubbery rot,” was seen in North Dakota and Minnesota this summer and was found in Wisconsin in 2019, Gary Secor, North Dakota State University Extension plant pathologist told farmers at Northern Plains Potato Growers' field day held Aug. 25, 2022, at Hoverson Farms near Larimore.

”It’s a new problem," Secor said.

The fungal disease, caused by geotrichum candidum, results in tubers that are damp and feel rubbery when they are squeezed, similar to the way they do when potatoes are infected with pink rot. The potatoes with rubbery rot are inedible.

Potatoes that have rubbery rot disease, which occurs at the end of growing season, smell like sour milk, Secor said.


Geotrichum candidum fungus is in soils worldwide, he said.

“It’s a very ubiquitous organism,” Secor said. "It is causing some serious problems. “

Secor declined to say where the potatoes he diagnosed with rubbery rot originated from in North Dakota and Minnesota.

In November 2019, the first case of rubbery rot was documented in potato fields in the United States. The potatoes were from a field in Bingham County, Idaho, and diagnosed with the disease at the University of Idaho, according to an article written by The American Phytopathological Society in St. Paul, Minnesota.

The Idaho potatoes that were infected with rubbery rot had been held in storage since harvest and were from a sandy loam field that was irrigated by an overhead system, the article said.

According to the article, rubbery rot has been sporadically reported in the United Kingdom and Korea and Australian potatoes with the disease were intercepted at a U.S. port. Meanwhile, rubbery rot also causes tomato rot in the United States, the article said.

Whether rubbery rot is difficult to manage is not known, Secor said. He and other researchers will study the fungus’ epidemiology to determine how to combat it.

Ann is a journalism veteran with nearly 40 years of reporting and editing experiences on a variety of topics including agriculture and business. Story ideas or questions can be sent to Ann by email at: abailey@agweek.com or phone at: 218-779-8093.
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