Late-Season Decline: A New Bacterial Disease of Corn Identified in the Texas Panhandle

Abstract

The genus Pantoea has historically been associated with two diseases of corn, Stewart's wilt caused by P. stewartii and necrotic or white leaf spots or streaks and stalk rot caused by P. ananatis. In 2020 and 2021, a sudden and unusual decline of corn stands was observed in corn fields in two counties in the Texas High Plains region. Symptoms observed included initial light green, elongated, slightly translucent, and nonchlorotic streaked lesions with nonwavy margins that developed on leaf blades during corn vegetative growth stages, with lesions becoming necrotic at the onset of crop reproduction. Additionally, stunting of affected plants, poor ear development, and stalk rot were associated with affected stands. Diagnosis of symptomatic tissues consistently recovered bacteria. BLAST searches of the partial 16S rRNA sequences of the bacterial isolates identified them as belonging to the genus Pantoea. Investigations of the pathogenicity of two bacterial isolates, B566 and B623, under greenhouse conditions relying on Koch's postulates resulted in the development of symptoms identical to those observed on symptomatic field corn plants. The two bacteria were also successfully recovered from symptomatic leaf and stem tissues, thus satisfying Koch's postulates. Sequence analysis showed that these isolates are closely related to P. ananatis but also phylogenetically distinct. The findings from this study provide evidence for a new disease of corn caused by two Pantoea species that can result in stand decline of infected corn plants.