Application of Fourier Transform Infrared Spectroscopy (FTIR) for Detection of Bacterial Fruit Blotch Disease On Plants.

Bacterial Fruit Blotch (BFB) plant disease is caused by Acidovorax avenae and affects worldwide production of cucurbits causing large economic losses. Currently there is zero tolerance for BFB in seed lots and transplant production facilities, yet no nondestructive, high throughput detection method exists that is sensitive enough to reliably detect BFB. Fourier Transform Infrared Spectroscopy (FTIR) may nondestructively detect BFB in seeds and seedlings. FTIR measures light absorbance by samples from a broadband light source.  A unique spectral signature differentiated BFB from other plant pathogens over a concentration range of 10⁸ to 10⁵ cfu/mL in buffer solution.  Leaves of cantaloupe (Cucumis melo) and watermelon (Citrullus lanatus) seedlings at the four-true-leaf stage were scanned by FTIR and spectral changes existed in BFB infected leaves before visible symptoms were noticed. Dry seeds, infected with BFB by hand inoculating flowers and confirmed by symptoms on seedlings, produced a different spectral profile compared to disease-free seeds. FTIR can differentiate disease free seeds and seedlings from those infected with BFB.