Maize Downy Mildew (Peronosclerospora neglecta) in Cambodia, Lao PDR, and Thailand

Abstract

Peronosclerospora species cause downy mildew diseases on maize (Zea mays) worldwide. Maize leaves with symptoms of downy mildew were collected from field crops in Cambodia, Lao PDR, and Thailand, during surveys between 2018 and 2022. Initial determination of the presence of downy mildew on specimens was determined microscopically by the presence of conidiophores and/or oospores in leaf tissue. Phylogenetic analyses of the cytochrome c oxidase subunit II (cox2) gene sequences showed that all specimens were Peronosclerospora neglecta. Reference specimens from Thailand were deposited at the Thai Plant Pathology Herbarium, Bangkok, Thailand, while those from Cambodia and Lao PDR were deposited at the Queensland Plant Pathology Herbarium, Australia. Peronosclerospora neglecta was widespread in field crops of maize in Cambodia, Lao PDR, and Thailand during the survey period. This is the first time that P. neglecta has been reported in Cambodia and Lao PDR. © 2024, Chiang Mai University. All rights reserved.