Surface soil moisture and stubble management practice effects on the progress of infection of wheat by Fusarium pseudograminearum

The influence of surface soil moisture and stubble management practices on the progress of infection of wheat by Fusarium pseudograminearum, the cause of crown rot, was assessed in a field trial at Moree in northern New South Wales during the growing seasons of 1994, 1995 and 1996 by analysis of infection progress curves. During the dry season of 1994, wheat was sown into dry surface soil. Increases in incidence of infection followed rainfall events that raised the water content of the surface soil above the equivalent of a water potential of –1.5 MPa. The rate of increase in incidence of infection was more uniform in the 1995 and 1996 seasons, which had more regular rainfall. The area under the infection progress curve (AUIPC) was consistently greater when stubble was retained on the surface compared with incorporation with a disc plough, and this difference was significant in 2 out of 3 years. Comparison of AUIPCs indicated greater epidemiological differences between stubble management treatments than did comparisons of incidence of infection at single points during the season.