Different vegetation spectral indices correlate highly to spatial patterns of corn yield (as shown below) and leaf area index (LAI). Wu et al. (2007; pdf) showed (based on Quickbird imagery; has a much finer resolution than Landsat) that MSAVI (Qi et al., 1994) is better than other indices, including NDVI, for remote sensing of corn LAI. Hollinger (2011) showed MSAVI correlates higher to corn yield spatial patterns than most indices, but other indices correlate very similarly to MSAVI. Below, Landsat-based MSAVI from V12 to V19 is correlated (linear regression) with corn yield by averaging clean yield points within the pixel extent (based on 4-meter spacing; approximately 56 yield points per pixel); a comparison of correlations with other indices based on reflectance and digital numbers (DNs) is shown after the correlation graphics. Landsat imagery should not be used for corn prior to V12 because soil has too strong of an influence or at VT and later due to the effect of tassels.