Identification of the Pathogen of a New Rice Leaf Spot Disease and the Differences between Leaf Spot Disease and Rice Blast

PurposeTo identify the pathogen and potential threat of a new rice leaf spot disease and potential threats of this disease to rice production, which occurred in Lingshui, Hainan Province in 2018.

Methods We carried out the identification of pathogen causing rice leaf spot disease by morphological classification combined with molecular biology methods, the investigation of early biological process of pathogen infection in rice, and the pathogenicity identification of pathogen on 13 rice varieties by spraying inoculation.

Results The pathogen caused leaf spot disease of rice in Hainan is fungi Curvularia lunata, belonging to Ascomycota, Dothideomycetes, Pleosporales, Pleosporaceae, Curvularia. The typical symptom of leaf spot disease is the formation of large oval brown spots on rice leaves of infected plants. Although the biological process of rice infection by C. lunata is similar to that of Magnaporthe oryzea, the time from conidial germination to mycelial expansion is shorter. The C. lunata pathogen showed obvious pathogenicity to 13 rice materials tested in this study.

ConclusionWe clarified that the pathogen caused rice leaf spot disease in Lingshui of Hainan Province is C. lunata, the typical symptoms of leaf spot disease are different from rice blast, and the pathogenicity of C. lunata to 13 rice materials tested in this study, including broad-spectrum blast resistant rice Digu. Our results are helpful for the correct recognition and effective control of rice disease, providing new information for rice disease resistance breeding.