FLYER: A Simple Yet Robust Model for Estimating Yield Loss from Rice False Smut Disease (Ustilaginoidea virens)

Rice False Smut (RFSm) is presently an internationally important fungal disease of rice. While the Yield Loss (YL) from this disease is reported in many countries, there exists no tool to instantly estimate the YL by visual field inspection. This study developed a simple model, FLYER, for this purpose. The model is run by two inputs: (i) fraction of productive but diseased tillers in a field and (ii) averaged number of smut balls present in the diseased panicles. FLYER was developed using data from Bangladesh, India and Japan. The driving algorithm of the model, the yield reduction in a diseased panicle as a function of number of smut balls present in the panicle, was validated with additional data from Bangladesh and Japan. When tested with independent data from fields infected naturally by RFSm, FLYER closely estimated the Yield Loss (YL, %) against observed datasets from Bangladesh (Root Mean Squared Deviation (RMSD ) = 1.15% YL), Egypt ( RMSD = 1.65% YL) and India ( RMSD = 1.68% YL). This model could contribute to rapid assessment of regional and variety-specific yield loss and strategic management of the disease on a field-by-field basis.