Deoxynivalenol levels and chemotype frequency in barley cultivars inoculated with two chemotypes of Fusarium graminearum

Abstract Corn kernels colonized by Fusarium graminearum were spread between lines of barley (Hordeum vulgare) in an irrigated Fusarium head blight (FHB) nursery at a 2 : 1 ratio of isolates producing 15-acetyldeoxynivalenol (15 ADON) to isolates producing 3-acetyldeoxynivalenol (3 ADON) (in 2008) or 1 : 1 ratio (in 2009, 2010). In 2008, it was the first use in this field of a 3 ADON isolate after 9 years of artificial inoculation with exclusively 15 ADON isolates. Sets of three 2-row and three 6-row cultivars were used as checks throughout the nursery, representing a range of susceptibility to FHB. Composites of these cultivars were prepared and analysed for per cent F. graminearum infection, chemotype frequency and levels of deoxynivalenol (DON), 3 ADON and 15 ADON. Seed infection by F. graminearum ranged from 83.5% (2009) to 98.5% (2010), with little difference across the nursery. In 2008, the chemotype distribution of F. graminearum and DON levels on infected kernels showed a several-fold difference fr...