Abstract
Foliar disease assessment especially in cereal crops requires a lot of time and precision if done on manual basis. Moreover, walking through plot during disease data collection can potentiality introduce some observer-caused errors in form of unnaturally transmitted spores (especially in case of wheat leaf rust). The disease assessment in cultivar mixtures becomes further complicated due to diverse range of disease intensity. This paper deals with the remote assessment of wheat leaf rust in cultivar mixtures and component purelines where the disease assessment was made through using percent reflectance at eight different wavelengths by using hand-held spectroradiometer. The spectroradiometer measurements indicated that severity of leaf rust could be assess at 650 nano meter (nm.), when plant were at growth stage 11. Because a linear relationship was found between leaf rust severity and light reflectance from the crop, the disease could readily and accurately assessed in cultivars mixtures without physical movement through the crop. These findings suggest that remote assessment by a spectroradiometer allows (i) objectivity, (ii) accuracy, and (iii) virtual elimination of observer - caused spore movement Key Words: Wheat, leaf rust, spectroradiometre, cultivars mixtures, remote assessment
