Southern Blight of Water Lily: The First Host Record of Agroathelia rolfsii on Nelumbo nucifera Discovered in Florida, U.S.A.

Nelumbo nucifera Gaertn. (Nelumbonaceae, Eudicots), also known as water lily or sacred lotus, is a nonnative and invasive plant commonly found in artificial ponds and natural lakes throughout Florida (UF-IFAS 2023; Wunderlin et al. 2023). In August 2020, a single sample of water lily plants showing large leaf spots were collected at a residence in Dunnellon, Marion County, Florida (80% disease prevalence with 40% leaf coverage). Symptoms and signs of the disease were necrotized adaxial leaf spots only, bordered by whitish mycelia and hyphae with clamp connections, and whitish to light brown sclerotia formed in the center (50% relative humidity, and a 12-h/12-h photoperiod). All inoculated leaves showed necrotized areas after one week and new sclerotia were observed floating on the water surface after three weeks. Fungal pathogen was reisolated and reidentified subsequently. Agroathelia rolfsii is the causal agent of southern blight, also known as grey rot, and is reported from at least in 260 plant genera, including specialty crops such as citrus, cucumber, pepper, peanuts, pumpkin, and strawberry (Farr and Rossman 2018). Agroathelia rolfsii usually causes lower stem, crown, and root rots; consequently, leaf spots are a noteworthy presentation of symptoms for this fungus.