Aerial Hyperspectral Near Range Spectrometry
Puccinia psidii (Fig. 1) is an invasive pathogen of global significance. Discovered in Brazil in 1884, it spread over Florida, Hawaii, Japan, China and finally reached Australia in 2010. Plant pathologists regard P. psidii (myrtle rust) as a threat to native Australian Myrtaceaedominated ecosystems, and to industries depending on this plant family (e.g. Forestry and Tea Tree Oil). Typically, rust fungi have few host species, however myrtle rust has already infected over 300 native Australian Myrtaceae in four years, the number of infections rising (Makinson, 2014). Severe damage on two endemic rainforest species has been reported recently for the first time (Carnegie et al., 2015). Glen (2007) published a comprehensive review on P. psidii with a special focus on the vulnerability of Australian ecosystems. It is imperative that monitoring of plant communities and ecosystems are initiated to fully understand the long term impact of this devastating invasive pathogen. Plant diseases like P. psidii alter the functioning and very often the phenotype of plants. Such changes cause plant stress and can be mirrored in varying plant’s spectral reflectance which depend on the origin of stress (Jackson, 1986). Vegetation indices are well known to perform very accurately detecting unspecific stress, and have recently been advanced to detect even disease specific plant stress. Specific disease indices (SDIs) have been successfully applied to classify e.g. healthy and Cercospora leaf spot, sugar beet rust and powdery mildew infected leaves with high balanced classification accuracies (Mahlein et al., 2013). Apart from hyperspectral signatures and images, chlorophyll fluorescence, RGB and thermographic images are used to quantify plant diseases. Both thermographic and multispectral sensors can be mounted on unmanned aerial vehicles for repeated deployment for acquisition of high temporal resolution data at very high spatial resolution. Ground truth data is necessary to develop new SDIs and to support remote sensing systems like satellites for global scale monitoring
Authors: Rene hans-Juergen Heim, Ian J. Wright, and Jens Oldeland
Keywords: Puccinia psidii, Myrtle Rust, Field Spectroscopy, UAS, Spectral Indices
Spectral Evolution is a leading manufacturer of field-portable UV-Vis-NIR remote sensing spectroradiometers and spectrometers for applications including geological remote sensing, ground-truthing, spectral remote sensing, environmental and climate research, crop and soil research, vegetative studies, forestry and canopy studies, radiometric calibration transfer, upwelling and downwelling measurement and more. Our UV-Vis-NIR spectrometers and spectroradiometers provide the best combination of high resolution and high sensitivity resulting in the most precise field portable instruments available on the market.
Spectral Evolution UV-Vis-NIR spectroradiometers provide:
- Fast, full-spectrum UV-Vis-NIR measurements – 350-2500 nm with just one scan
- Superior reliability in the field with 100% diode array optics with no moving parts
- Wireless Bluetooth® Connection
- Lithium-ion rechargeable batteries for field use
- Lightweight and rugged
- Rugged handheld tablet for field use running DARWin™ LT on Windows 10 with digital camera, and GPS
- Field switchable optics for varying target sizes and measurement modes
All Spectral Evolution UV-Vis-NIR spectroradiometers include our exclusive DARWin™ SP Data Acquisition and Analysis software for one-touch, full range spectroscopic analysis of samples. DARWin™ SP automatically saves data as ASCII files for use with 3rd party software without post-processing.