Population Dynamics Between Fusarium pseudograminearum and Bipolaris sorokiniana in Wheat Stems Using Real-Time qPCR

Moya-Elizondo, E. A., Jacobsen, B. J., Hogg, A. C., and Dyer, A. T. 2011. Population dynamics between Fusarium pseudograminearum and Bipolaris sorokiniana in wheat stems using real-time qPCR. Plant Dis. 95:1089-1098. Fusarium pseudograminearum and Bipolaris sorokiniana are causal agents of Fusarium crown rot and common root rot, respectively, of wheat and cause significant losses worldwide. Understanding the population dynamics between these two pathogens at late stages of wheat development is needed. The effect of E pseudograminearum and B. sorokiniana inocula applied singly or in mixtures at seeding to spring wheat 'Hank' was measured using seedling stand, grain yield, and pathogen populations in the first internode at heading, milk, and harvest stage of wheat development using real-time quantitative polymerase chain reaction. High and low rates of E pseudograminearum inoculum reduced B. sorokiniana populations in field trials but B. sorokiniana inoculations did not affect F pseudograminearum populations. Populations of both pathogens increased front heading until harvest, with E psendograminearum colonizing lower internodes earlier than B. sorokiniana. Neither pathogen prevented infection by the other in the first internode of wheat stems. Inoculations increased incidence of infection and co-infection relative to natural settings observed for both pathogens. At the seedling stage, both fungi, individually or combined, reduced the seedling stands when compared with a non-inoculated control for the three location years. Grain yield and E pseudograminearum populations were inversely correlated, while B. sorokiniana populations were not correlated with yield.