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POSTERS: Pathogen detection, quantification and diagnosis

Fungal pathogens associated with rice seedling disease in the Southern United States
Shankar Gaire - Texas A&M AgriLife Research Center. Xin-Gen Zhou- Texas A&M AgriLife Research Center, Young-Ki Jo- Texas A&M University, Jun Shi- Mianyang Academy of Agricultural Sciences, Jun Shi- Texas A&M AgriLife Research Center

Seedling disease, also known as seedling blight or damping off, is a disease complex caused by several seedborne and soilborne pathogens. The distribution and importance of causal pathogens in the rice-producing regions in the U.S. remain largely unknown. Survey was conducted in 2018 from 35 rice fields of Arkansas (6), Louisiana (6), Mississippi (4) and Texas (19), and 10 symptomatic rice seedlings were collected from each field. Fungi were isolated from the roots and mesocotyls, and their pathogenicity was determined in a plant growth chamber. Pathogenic fungi were identified based on morphology and internal transcribed spacer rRNA gene sequences. Rhizoctonia solani, Sclerotium rolfsii, and Fusarium spp. were confirmed to cause seedling disease in 42, 10 and 8% of plant samples collected, respectively. Results of this study provide better understanding of the distribution and frequency of fungal pathogens associated with rice seedling disease in the Southern U.S., which will serve as the foundation to develop and implement effective management options for control of this important disease in rice.