Oklahoma State University Stillwater, Oklahoma, United States
Abstract Text: Since its first description in the Rio Grande Valley of Texas in 1945, corn stunt has expanded across the Neotropics. The corn stunt spiroplasma (Spiroplasma kunkelii) is the most important pathogen associated with the disease in the U.S., due to its widespread distribution in the Rio Grande Valley region and persistent occurrence in California and Florida. During the 2024 growing season, symptomatic corn leaf samples were collected at commercial and experimental field sites located at OK, KS, MO, AR, NE, SD, MN, WI, IN, NY, and AL. Detection and identification of S. kunkelii were performed through a polymerase chain reaction targeting a section of the spiralin gene, followed by amplicon sequencing. This study provides the first report of the pathogen S. kunkelii associated with corn stunt symptoms distributed across six counties in OK, 14 counties in KS, two counties in MO and AR, four counties in NY, and one county in NE, SD, WI, MN, IN, and AL. In addition, temporal and spatial distribution of corn stunt symptoms in an experimental late-planted corn field located at Stillwater, OK, were visually recorded during four weeks in the 2024 growing season. A total of 25,500 corn plants were scouted by corn stunt sunt symptoms between 08/15/2024 to 09/06/2024. Symptoms of corn stunt were first observed at field borders and progressed towards the center of field. The recent incursion of S. kunkelii to northward U.S. states raises the need to establish regional monitoring programs targeting the distribution of corn stunt in future growing seasons.
