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POSTERS: Integrated Pest Management II

P-300 - Nitrogen dioxide fumigation reduces seedborne Verticillium dahliae and Peronospora effusa in spinach seeds

Tuesday, August 5, 2025
9:30 AM - 10:15 AM HST
Location: Exhibit Hall 3
Abstract Text:

The global spinach (Spinacia oleracea) seed trade has significantly contributed to the spread of the fungal pathogen, Verticillium dahliae and the oomycete pathogen, Peronospora effusa. Seedborne V. dahliae causes Verticillium wilt in mature spinach and affects a wide range of rotational crops, including lettuce (Lactuca sativa). In contrast, P. effusa is host-specific and causes the destructive spinach downy mildew. Managing seedborne pathogens remains challenging. This study aimed to limit the seedborne V. dahliae and P. effusa using fumigation with 3% nitrogen dioxide (NO₂) gas for three days. The treatment significantly reduced both external and internal V. dahliae by 60% to 91% and completely eradicated P. effusa from spinach seeds. Notably, NO₂ fumigation also enhanced seed germination and plant growth unlike other fumigants and treatments that adversely affect seed viability. These findings highlight NO₂ fumigation as an effective method for controlling V. dahliae and P. effusa in spinach seeds. The approach may also be adaptable to organic seeds and holds promise for managing seedborne pathogens in many other crops.