We will investigate the development of a low-cost portable spectral imaging device that can be appended to a phone and used for two purposes: first, early detection of diseases in plants where symptoms are not visible to the naked eye and second, inspection of planting materials to determine if they are disease-free. There has been a growing set of examples of diseases which can be detected early through the use of spectrometry and hyperspectral imaging for crops such as rice, wheat, citrus and tomato (Sankaran et al, 2010).
Laser-induced fluorescence spectrometry, for example, has been shown to be an effective method for early-onset and non-destructive disease detection. Two types of fluorescence are produced by green leaves: (i) blue-green fluorescence in about the 400–600 nm range, and (ii) chlorophyll fluorescence in about the 650–800 nm range. Spectroscopic analysis of these can be utilized to identify signatures corresponding to particular diseases, as well as identifying nutrient deficiencies, and stresses from environmental conditions.