Comparison of Airborne Multispectral and Hyperspectral Imagery for Mapping Cotton Root Rot

Abstract

Cotton root rot, caused by the soilborne fungus Phymatotrichum omnivorum, is a major cotton disease affecting cotton production in the southwestern and south central U.S. Accurate delineation of root rot infestations is necessary for cost-effective management of the disease. The objective of this study was to compare airborne multispectral and hyperspectral imagery for detecting and mapping root rot areas in cotton fields. Two center-pivot irrigated fields in south Texas were selected for this study. Airborne 3-band multispectral and 128-band hyperspectral imagery was taken from the two fields shortly before harvest in 2002 when the infested areas were fully expressed for the season. Both types of imagery and the principal component images derived from the hyperspectral imagery were classified into 2-10 spectral classes using unsupervised classification techniques. The individual spectral classes were then grouped into infested and non-infested zones. Accuracy assessment on the two-zone classification maps showed that both types of imagery as well as the principal component imagery equally accurately identified root rot areas within the fields. These results indicate that both airborne multispectral and hyperspectral imagery can be used for assessing root rot infestations within cotton fields.