Taking shortcuts: lowering harvest height to restrict colonisation of cereal stubble by Fusarium pseudograminearum

Context. Many wheat producers are increasing the biomass of cereal stubble retained after harvest through the adoption of stripper front harvesters, which result in taller standing stubble. Aims. We investigated whether tallerstubble affectsthe survival and dispersal of Fusarium pseudograminearum (Fp), the causative agent of Fusarium crown rot (FCR). Methods. Field experiments at two sites in northern New South Wales were run for 3 years to investigate whether taller cereal stubble in Year 1 facilitated additional Fp colonisation, and subsequent effects on dispersal of Fp inoculum from chickpea harvest in Year 2 and FCR infection and expression in cereal crops in Year 3. Culturing and quantitative polymerase chain reaction (qPCR) methods assessed Fp colonisation and future disease risks. Key results. In taller cereal stubble, Fp colonised an additional 91–92% of the stubble length in the 6 months post-harvest and persisted at higher levels for at least 1 year than did the shorter cereal stubble. Cutting cereal stubble short (in Year 1) therefore successfully restricted further colonisation by Fp. Significant displacement of Fp in the crown 6 months post-harvest resulted in significant decreases in Fp DNA overall; however, long-term survival of Fp was observed 10–20 cm above the crown. Conclusions. Different residue management scenarios did not increase FCR risk for Year 3, likely owing to high inoculum levels across all treatments and unseasonably wet conditions in Years 2–3. Implications. We provide important field-validation of Fp colonisation in standing cereal stubble and discuss implications for FCR management across regions and seasons.