Geography and Environmental Resource

Aerial imaging provides a landscape view of crop fields that can be utilized to monitor plant diseases. Phymatotrichopsis root rot (PRR) is a serious root rot disease affecting several dicotyledonous hosts, including the perennial forage crop alfalfa. PRR disease causes stand loss by spreading as circular to irregular diseased areas that increase over time, but disease progression in alfalfa fields is poorly understood. The objectives of this study were to develop a workflow to produce PRR disease maps from sets of high-resolution red, green and blue (RGB) images acquired from two different platforms and to assess the feasibility of using these PRR disease maps to monitor disease progression in alfalfa fields. Aerial RGB images, two from unmanned aircraft systems (UAS) and four images from a manned aircraft platform were acquired at different time points during the 2014-2015 growing seasons from a center-pivot irrigated, PRR-infested alfalfa field near Burneyville, OK. Supervised classification of images acquired from both platforms were performed using three spectral signatures: image-specific, UAS-platform-specific and manned-aircraft platform-specific. Our results showed that the UAS-platform-specific spectral signature was most efficient for classifying images acquired with the UAS, with accuracy ranging from 90 to 96%. In contrast, manned-aircraft-acquired images classified using image-specific spectral signatures yielded 95 to 100% accuracy. The effect of hue, saturation and value color space transformations (HSV and Hrot60SV) on classification accuracy was determined, but the accuracy estimates showed no improvement in their efficiency compared to the RGB color space. Finally, the data showed that the classification of the bare ground increased by 74% during the study period, indicating the extent of alfalfa stand loss caused by PRR disease. Thus, this study showed the utility of high-resolution RGB aerial images for monitoring PRR disease spread in alfalfa.

These papers examine and explore policy issues within the scope of the Institute's mission and in the tradition of the University. The Paul Simon Public Policy Institute acts on significant and controversial issues impacting the region, the state, the nation, and the world. The Institute is committed to developing and working to implement approaches that could bring concrete, positive results in tackling some of the most difficult challenges in the public policy arena. The Institute focuses its efforts on fostering ethical conduct in government, opportunity and fair treatment for people in America and throughout the world, and promoting responsible citizenship for all Americans-but particularly for young Americans. The Institute executes its mission by conducting nationally known public opinion polls (The Simon Institute Poll™ and The Southern Illinois Poll™) to inform decision makers and citizens, and publishing analysis of public policy issues in an occasional paper (The Simon Review). The Institute also provides and supervises paid internships and other learning opportunities for university students, hosts lectures and conferences with noted leaders in public policy, journalism and other fields, and provides leadership and civic education opportunities for high school students.

Scholars have established that our geographic environmentsincluding infrastructure for walking and food availability-contribute to the current obesity epidemic in the United States. However, the relationship between food, walkability, and obesity has largely only been investigated in large urban areas. Further, many studies have not taken an in-depth look at the spatial fabric of walkability, food, and obesity. The purpose of this study was twofold: 1) to explore reliable methods, using sociodemographic census data, for estimating obesity at the neighborhood level in one region of the U.S. made up of rural areas and small townssouthern Illinois; and 2) to investigate the ways that the food environment and walkability correlate with obesity across neighborhoods with different geographies, population densities, and socio-demographic characteristics. This study uses spatial analysis techniques and GIS, chiefly geographically weighted multivariate linear regression and cluster analysis, to estimate obesity at the census block group level. Walkability and the food environment are investigated in depth before the relationship between obesity and the built environment is analyzed using GIS and spatial analysis. The study finds that the influence of various food and walkability measures on obesity is spatially varied and significantly mediated by socio-demographic factors. The study concludes that the relationship between obesity and the built environment can be studied quantitatively in study areas of any size or population density but an open-minded approach toward measures must be taken and geographic variation cannot be ignored. This