Application of Thermal Imaging Sensor to Early Detect Powdery Mildew Disease in Wheat

The potential of remote sensing as a tool to identify Powdery mildew disease in an early infection stage and to accurately quantify the severity of infection is crucial in plant disease assessment and management. Powdery mildew is one of the most harmful disease causing great losses in wheat yield. Remote sensing data were obtained in the thermal infrared spectral ranges. A greenhouse study was conducted to assess changes in leaf temperature of wheat plants during infection by powdery mildew to evaluate leaf reflectance measurements. Thermal images of plant disease under different environmental conditions in the field are a cutting-edge research. The variations in temperature between infected and healthy leaves of wheat and the variation between air and leaf-surface temperatures under greenhouse conditions were sensed for early detection of disease. Results revealed that infection with powdery mildew pathogen induced changes in leaf temperature from 0.37 ?C (after one hour from the infection) to 0.78 ?C at (21 days after infection with the pathogen) and metabolism, contributing to a distinct thermal signature characterizing the early and late phases of the infection. These changes in leaf temperature during Powdery mildew development resulted in a considerable heterogeneity in temperature distribution of infected leaves. The maximum temperature difference within a thermogram of wheat leaves allowed the discrimination between healthy and infected leaves before visible symptoms appeared.