Two recently confirmed, untreatable plant diseases are threatening Missouri's two most valuable crops-corn and soybeans-raising concerns over potentially severe agricultural and economic losses in the state.
Corn and soybeans generate more than $5 billion annually in Missouri, according to the U.S. Department of Agriculture. Both crops are now facing newly identified pathogens: red crown rot in soybeans and corn stunt disease in corn. State agriculture officials confirmed the presence of both diseases during the 2024 growing season.
Excessive rainfall earlier in the year delayed planting across much of Missouri, which researchers say may delay visible symptoms of the diseases until late summer or early fall. Plant pathologist Mandy Bish of the University of Missouri, who specializes in crop disease identification and management, is leading efforts to monitor the outbreaks.
Red crown rot: a soil-borne risk to soybeans
Red crown rot is a fungal disease that spreads through soil and currently has no effective treatment or containment method once established. According to Bish, infected soybean fields can suffer yield losses of up to 70–80% in severe cases.
The disease was first identified in U.S. peanut crops in Georgia in the 1960s and later in Illinois soybean fields in 2018. It has now been confirmed in Missouri's Marion and Audrain counties, though Bish suspects wider distribution.
"The soybeans that are infected with red crown rot look a lot like other things that we already know of that can cause sickness," Bish said. "By the time we start to see symptoms in a field, there's not much we can do at that point."
Containing the disease would require sanitizing farm equipment between fields, a measure Bish described as currently impractical. She emphasized the need for longer-term research and development to identify viable countermeasures.
Terry Schwoeppe, a member of the Missouri Soybean Commission, said he was unaware the disease had been detected in the state, indicating limited awareness among producers.
Corn stunt: an airborne bacterial threat
Corn stunt disease is caused by a bacterium transmitted by corn leafhoppers, a recently observed insect in Missouri. According to the Crop Protection Network, the insects have been detected in at least three counties: Lawrence, Vernon, and Boone.
Bish warned that the disease can lead to complete yield loss under certain conditions. "Some of our corn that already has ears on it and is tasseling and is happy will be OK," she said. "But some of our corn that was planted later in the year due to all the rain- it could have an effect on them."
The University of Missouri has advised farmers to begin scouting for corn stunt symptoms, which include leaf chlorosis, reddening of leaf tips, stunted growth, and malformed ears with missing kernels. As with red crown rot, there is no known treatment once symptoms develop.
Agricultural authorities are continuing to monitor the spread of both diseases and are encouraging producers to report suspected cases to local extension offices.
