Submitted to: Mid-South Entomologists online journal
Publication Type: Abstract Only
Publication Acceptance Date: 10/26/2007
Publication Date: 1/10/2008
Citation: English, P. J., Defauw, S. L., Smith, J. W., Willers, J. L. 2008. Management Zone Delineation and Image Resolution Issues in the Site-Specific Control of Tarnished Plant Bugs in Cotton. Meeting Abstract.
Technical Abstract: Precision-based agricultural application of insecticide relies on a non-random distribution of pests. Tarnished plant bugs (Lygus lineolaris) are known to prefer vigorously growing patches of cotton, therefore, management zones may be readily defined using NDVI (Normalized Difference Vegetation Index). Field-scale NDVI variability is the combined result of crop response to intrinsic field properties (i.e., soils, drainage, and planting preparations, etc.) as well as weather-related conditions. The objective of this study was to evaluate the interactions of field-scale heterogeneity and the spatial resolution of aerial imagery and their effects on delineating transitions in management zone boundaries for the site-specific control of L. lineolaris in cotton. We found that the aerial extents of non-autocorrelated patches increased as image resolution decreased. At 1 m resolution, field-scale percentages of non-autocorrelated areas ranged from 19.4-24.5% (with a mean of 20.7%). However, at 2 m resolution, the range of non-autocorrelated areas expanded to 32.3-43.6% (with a mean of 37.6%). The non-autocorrelated patches represented as narrow linear features denote sharp transitions between potential management zones, whereas irregularly-shaped, omni-directional patches define highly-variable transitions between zones. These latter patches pose problems because they contain highly heterogeneous habitat quality that may not be properly identified in a site-specific application (and in all likelihood not sprayed), thereby serving as refugia and loci for reinfestation of the field by TPBs. The optimal resolution for identifying these heterogeneous zones appears to be related to row spacing and the cotton variety’s ability to close the canopy. However, this hypothesis will need to be tested using higher resolution imagery, and software capable of processing large acre fields (greater than 100 acres) at resolutions greater than 1 meter.