Fourier transform infrared spectrum pre-processing technique selection for detecting PYLCV-infected chilli plants

•Pepper Yellow Leaf Curl Virus (PYLCV) can reduce the productivity of chilli plants by between 20% and 100%.•The disease exhibits the same symptoms as plants with mineral and water deficiencies so is often not correctly detected.•We propose optimized Fourier Transform Infrared Spectroscopy spectra pre-processing to detect PYLCV-infected chilli plants.•We choose the method from denoising, normalizing and baseline correction that delivers the highest classification accuracy.•Savitzky-Golay 1st derivative pre-processing was the best method, enabling subsequent classification accuracy of up to 100%.