Pathogen Composition and Fungicide Sensitivity in Rice Spikelet Rot Disease.

Rice spikelet rot disease (RSRD) is an emerging threat to rice crops, with sporadic but severe outbreaks in China in recent years. The composition of its pathogenic fungi has not been consistently identified, and chemical control methods remain unclear. This study aims to characterize the pathogen species responsible for RSRD and develop effective control strategies. Regional variations in disease symptoms and pathogen compositions were analyzed, which led to the identification of six novel pathogens, including Fusarium tanahbumbuense, Alternaria gaisen, Curvularia verruculosa, Curvularia brachyspora, Curvularia muehlenbeckiae, and Curvularia hominis. The pathogenic composition of RSRD exhibited considerable variation across different latitudes within China. Specifically, Alternaria spp. predominated in the Heilongjiang and Liaoning Provinces. Whereas Fusarium spp. and Curvularia spp. were more prevalent in the Hainan and Fujian Provinces. In contrast, Fusarium spp. and Alternaria spp. were the dominant pathogens in the Anhui and Jiangsu Provinces. Furthermore, an assessment of the sensitivity of these predominant pathogens to four chemical compounds was conducted, which led to the identification of potential fungicides for effective disease control. This research provides valuable insights into the pathogenic profile of RSRD across different regions and offers strategic recommendations for fungicide-based management of the disease.