We report on the use of leaf diffuse reflectance spectroscopy for plant disease
detection. A smartphone-operated, compact diffused reflectance spectrophotometer
is used for field collection of leaf diffuse reflectance spectra to enable
pre-symptomatic detection of the progression of potato late blight disease post
inoculation with oomycete pathogenPhytophthora infestans.
Neural-network-based analysis predicts infection with >96% accuracy, only 24
h after inoculation with the pathogen, and nine days before visual late blight
symptoms appear. Our study demonstrates the potential of using portable optical
spectroscopy in tandem with machine learning analysis for early diagnosis of
plant diseases.