On a Pike County, Illinois farm, a seventh-generation grower named Ron Hoskin has spent nearly a decade watching a soil-borne fungus chip away at his soybean fields, year after year, with no real end in sight. His family's farm was where red crown rot first turned up in the Midwest, and in August 2026 he found it again in five of his fields. Hoskin farms 1,600 acres of corn and soybeans, and he says he'll plant soybeans again next year if conditions hold steady.
Hoskin's daughter, Reagan Hoskin, discovered the disease in 2018 while surveying the family's soybean fields, and the University of Illinois later diagnosed it as red crown rot, according to the Chicago Tribune. Matt Montgomery, an agronomy education lead at Beck's Hybrids, has called the Hoskin farm patient zero for the outbreak, and the disease appears to have radiated outward from Pike County across Midwest soybean country since that first discovery. The fungus attacks the roots of growing soybean plants, favors warm soil and moist air, and in severe cases can cut yields by as much as 60%, per the Tribune's reporting.
The numbers on Hoskin's own land tell the story. An affected field needed 60 bushels of soybeans just to break even in 2020, but he harvested only 21 bushels from that field that year. Across the wider outbreak, some fields have seen yields drop from 70 or 80 bushels per acre down to the teens, the Tribune reports. Infected plants often show yellow leaves and premature browning, along with red pimple-like structures at the base of the stem — symptoms that typically don't show up until near the start of August.
A Pathogen With a Long Southern History and a Sudden Northern Leap
Red crown rot isn't new to American agriculture. The fungus, known scientifically as Calonectria ilicicola, was first identified on U.S. peanuts in 1965 and on North Carolina soybeans in 1972, according to the Crop Protection Network. It stayed almost entirely confined to southeastern states for close to 50 years before turning up in Illinois in 2018, and the same infected-southern-soybeans description matches what the Tribune found on the Hoskin farm and beyond. Genetic research suggests the Illinois cases most likely weren't caused by fungal spread traveling up from the Southeast, leaving the exact path the pathogen took an open question.
That uncertainty runs deep among the people studying it. Experts disagree on how red crown rot actually travels between fields and states, with theories pointing to contaminated soil carried by farm equipment or spread through wind, but no consensus has emerged. The jumps have been striking in their distance: when the University of Minnesota Extension confirmed its first case in Rock County in August 2025, the infected field sat more than 400 miles from the nearest previously known infection site in northwestern Illinois, according to the university's Extension office. Wisconsin logged its first case just days after Minnesota's in August 2025, when researcher Smith found a 10-foot-diameter circle of affected crops, and the state logged a second case along its border with Minnesota in August 2026.
From Isolated Find to Corn Belt-Level Threat
By 2025, red crown rot had become a Corn Belt-level disease, spreading to other Illinois and Midwest locations after its initial 2024 expansion. Illinois, Indiana, and Missouri each now have the disease confirmed in more than 10 counties, and Boris Camiletti has logged many of the Illinois cases on the Crop Protection Network's tracking map. U.S. soybean yield losses tied to the disease jumped from 121,354 bushels in 2024 to an estimated 7.7 million bushels in 2025, with most of that loss concentrated in Illinois and Indiana, per the Crop Protection Network's March 2026 analysis.
The stakes are especially high in Illinois, which is the nation's top soybean-producing state and generates billions of dollars annually from the crop, per USDA figures cited in the Tribune's reporting. Damon Smith has suggested that climate change may be contributing to the disease's rise, though that link is described as a contributing factor rather than a settled cause. Midwestern farmers reported observing symptoms again in mid-July 2026, and the disease's footprint has kept expanding since 2025.
New Chemical Tool Offers Only a Delay, Not a Cure
Growers finally got a federally approved chemical option in November 2025, when the U.S. Environmental Protection Agency registered Syngenta's Victrato seed treatment, built on Tymirium technology with the active ingredient cyclobutrifluram, according to AgWired. It's the first federally labeled seed treatment aimed specifically at red crown rot in soybeans. Ron Hoskin planted soybeans treated with Victrato in 2026, but the treatment only delayed his fields' symptoms rather than preventing them outright, the Tribune reports. Calvin Koeller, whose farm developed red crown rot in 2025, plans to keep using Victrato in 2027 if his results remain favorable.
No soybean variety is known to be fully resistant to the disease, though some are considered partially resistant and factor into an overall three-pronged prevention approach that also includes seed treatments and managing plant stress. Hoskin hasn't tilled for soybeans since 1986, and switching to strip tilling — which some see as a way to disrupt the fungus in the soil — would cost him roughly $300,000 in new equipment, according to the Tribune. Crop rotation between corn and soybeans typically helps maintain soil health, but agronomic guidance from Ohio State University Extension notes that the fungus can also infect alternative legume hosts including red clover, white clover, crimson clover, vetch, and alfalfa — meaning standard rotations may not eliminate it from infested ground.
Why the Fungus Is So Hard to Root Out
Part of the problem is that red crown rot is thought to linger in soil year-round, and infected fields remain contaminated even when no crops are present, since the fungus survives as microscopic structures called microsclerotia. Purdue University Extension has documented 2026 field symptoms appearing at the beginning pod, or R3, growth stage in Indiana fields with a history of the disease, and those microsclerotia stay dormant until warm, wet soil conditions trigger germination, per the Purdue Extension. The disease also tends to spread in patches across a farm rather than uniformly, which can make it easy to miss during a routine field pass.
Misdiagnosis has been a recurring issue. Agronomists report that the yellowing and browning caused by red crown rot look nearly identical to Sudden Death Syndrome and Brown Stem Rot, meaning farmers often need to dig up root crowns and check for reddish discoloration and small growths called perithecia to tell the diseases apart. To get ahead of that problem, University of Illinois researchers are training AI models to detect infected fields using satellite imagery, learning from manually marked images of confirmed cases. The University of Illinois has also set up a red crown rot test plot directly on the Hoskin farm, turning the place where the disease was first found into a site for studying how to fight it.
