Effects of seed-borne Bipolaris sorokiniana on barley seed and seedling health

Bipolaris sorokiniana (teleomorph: Cochliobolus sativus) is a pathogen that can significantly limit the production of barley (Hordeum vulgare), causing plant diseases such as seedling blight, common root rot, foliar spot blotch, and kernel black point. Recently, high levels of seed-borne B. sorokiniana (90--100% infection) have been reported in 2-rowed barley produced in Manitoba. Seed-borne B. sorokiniana can spread inoculum and potentially lower the value of seed if germination, emergence, and yield are compromised. Effects of seed-borne B. sorokiniana were assessed using seven different barley seed lots having different levels of infection. Seed lots were designated to infection categories where 'clean/slight' = 0--25%, 'moderate' = 26--50%, 'severe' = 51--75%, and 'extreme' = 76--100% infection. Three systemic fungicide seed treatments, Charter, Dividend XL RTA, and Raxil 250 FL, were evaluated for their role in controlling or reducing the effects of seed-borne B. sorokiniana, in both field and controlled environments. In addition, the influence of soil temperature (18°C vs. 26°C) and seeding depth (40 vs. 80mm) were evaluated for their effect on emergence and seedling blight. (Abstract shortened by UMI.)...