Influence of Inoculation Timing and Pathogen Combination on Fusarium Head Blight Development in Winter Wheat

Fusarium head blight (FHB) is caused by a complex of Fusarium species, including F. graminearum and F. poae . The effect of inoculation timing on disease following single or combined inoculations with these species remains unclear. This study evaluated area under the disease progress curve (AUDPC), Fusarium ‐damaged kernels (FDK), thousand‐kernel weight (TKW), and species DNA after inoculation of winter wheat cv. SS8641 with F. poae , F. graminearum alone or combined under controlled conditions. Plants were inoculated 0, +3, +6 or + 9 days relative to complete heading/early anthesis. Treatment and inoculation timing significantly affected AUDPC, FDK and TKW ( p < 0.0001); the treatment × inoculation timing interaction was significant for TKW ( p < 0.0001), but not for AUDPC ( p = 0.73) or FDK ( p = 0.40). At 0 days, AUDPC was 69.2, 889.4 and 639.6 for F. poae alone, F. graminearum alone and combined inoculation, respectively; FDK was 6.6%, 73.1% and 52.9%, respectively. TKW was lowest at 0 days in treatments containing F. graminearum (11.8–15.9 g) compared with F. poae alone (35.2 g) and the mock control (37.0 g). In FDK fractions, F. poae DNA was undetected in co‐inoculated samples, whereas F. graminearum DNA did not differ significantly between single‐species and co‐inoculation treatments ( p = 0.119). These results indicate that disease and kernel‐weight responses were primarily driven by F. graminearum and that co‐inoculation with F. poae did not significantly alter disease outcomes or F. graminearum DNA accumulation relative to F. graminearum alone under the conditions tested.