Red Crown Rot Map

Red crown rot of soybean, caused by the fungus Calonectria ilicicola, is an emerging disease in the Midwest. Although the disease was first found in the United States in 1972 (North Carolina), and soon after in additional states in the southeastern U.S. and along the coast of the Atlantic Ocean, the disease has now emerged in the Midwest, beginning in 2018, when it was found in Illinois for the first time. Since then, the disease has been observed in additional midwestern states.

This map strives to capture confirmed observations of red crown rot, with a major focus on observations in states where the disease has made its first appearance within the last few years. The map also contains some historical observations where red crown had been confirmed several years ago. Historical observations by county/parish can be difficult to track down; therefore, counties in which the disease was reported several years ago, may not appear on this map. The map will continually be updated as new observations are confirmed as well as when historical data are found.

Research focused on best management practices for red crown rot are ongoing. Based on historical research and recent research, a few fungicide seed treatments may provide some suppression of the disease. Crop rotation with non-hosts may also help reduce inoculum of the red crown rot fungus in an infested field. The red crown rot fungus actively infects soybean roots when soil temperatures are between 77 and 86°F, so the planting date and associated soil temperature also may influence red crown rot severity. Cleaning equipment to remove soil before moving to a new field may also help reduce the spread of the red crown rot fungus to a new field.