Early Detection of Wheat Fusarium Head Blight During the Incubation Period Using FTIR-PAS

The apparent normalcy of wheat during the incubation period of Fusarium head blight (FHB) makes early diagnosis challenging. This study employed Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) to conduct layer-by-layer scanning of wheat leaves during the disease outbreak stage and performed a differential spectral analysis. Spectral information was collected from five sites (D0~D4) on diseased leaves at reducing distances from the lesion caused by the Fusarium graminearum pathogen. The results revealed that the disease caused an increase in spectral similarity between deeper and shallower layers. The spectra of leaves, after removing the D0 background, showed a correlation of 83.5% to that of the pathogen, and the similarity increased at sites closer to the lesion, suggesting that the original spectra captured a large amount of hidden information related to the pathogen. With the threshold for the absorption intensity ratio of R1650/1050 for background-subtracted spectra set at 0.5, the optimal overall accuracy and F1-score were 86.0% and 0.89 for diagnosing outbreak-stage samples, respectively, while for incubation-period samples, they were 82.5% and 0.83. These results elucidate the mechanism of using FTIR-PAS to diagnose FHB during its incubation period, providing a theoretical and technical foundation for detecting disease information in other crops.