Tracking wheat curl mite movement: a remote sensing approach

The wheat curl mite (WCM) is responsible for transmitting wheat streak mosaic virus (WSMV) and two other viruses to winter wheat. To prevent severe economic loss due to these viruses, it is important to understand mite movement and virus spread. This virus complex causes chlorosis and stunting, symptoms that can be remotely sensed. Remote sensing data can be used to assist in the spatial interpolation of a variable of interest with cokriging. In August of 2007 and 2008, small plots of simulated volunteer wheat were planted in the middle of a fallow wheat field and plots were infested with WCMs. Mite density in source plots was determined in August and September. Wheat susceptible to WCM-vectored viruses was planted surrounding plots in September. WCM density was determined at sampling points established around the plots in late fall, and virus presence, chlorophyll content, and leaf area index was determined in the spring to provide ground-truth estimates. Airborne hyperspectral remote sensing data was obtained in the spring of 2008 and 2009. Cokriging was used in a geographic information system to characterize the spatial pattern of virus symptoms. Cokriging revealed that virus spread occurred in an oval pattern surrounding source plots with greater spread south and east of WCM source plots. The extent of virus symptom spread predicted by cokriging was greater when WCM density in source plots was higher.