Assessing Cotton Stalk Destruction with Herbicides Using Remote Sensing Technology

Control of cotton stalk regrowth with herbicides on standing or shredded cotton provides an alternative method for post-harvest destruction of cotton stalks. Field experiments were conducted in 2002 and 2003 in the Rio Grande Valley of south Texas to assess the effectiveness of different herbicide treatments for cotton regrowth control using remote sensing technology. Eight treatments (combinations of herbicides and application timings) in 2002 and six treatments in 2004 arranged in a randomized complete block were evaluated on shredded cotton plots. Airborne color-infrared (CIR) imagery was acquired from the test plots in both years shortly before the state-mandated date for cotton destruction. Ground reflectance spectra and visual ratings ranging from no live plants to mostly healthy plants were also obtained from each plot. The reflectance spectra showed differences in regrowth among the treatments. The airborne CIR imagery provided limited visual differentiation among the treatments because of the small amount of regrowth. For quantitative analysis, the green, red, and near-infrared bands of the CIR imagery and four vegetation indices derived from the three bands were used as spectral variables to compare the differences among the treatments for each experiment. Statistical analysis showed that the spectral variables were able to identify the differences among the treatments as detected by the ground observations.