Effect of Volunteer Corn Density On Sugarbeet Yield.

A field study was conducted in 2010 to quantify the effect of volunteer corn density on sugarbeet yield loss.  The objective of this study was to determine whether remote sensing or light measurements taken mid-season were correlated to sugarbeet yield loss. Volunteer corn was planted into the sugarbeet row at 0, 0.3, 0.5, 0.8, 1.2 and 1.6 plants/m². Plots were 3 m wide by 9 m long and arranged in a randomized complete block design with four replications.  Glyphosate was applied as needed to remove weeds other than volunteer corn.  Light transmittance (LT) and leaf area index (LAI) measurements were taken above and below the sugarbeet canopy within each plot on July 14.  Remote sensing imagery was taken via AEROCam on August 13 in red, green, and near infrared (NIR) bands with a spatial resolution of 0.25 m².  Spectral values were calculated for similar locations as LT and LAI measurements, and analyzed in ERDAS IMAGINE software.  Sugarbeet root yield, percent sucrose content and recoverable sucrose were measured at harvest on October 5.  Measured LAI above the sugarbeet canopy was strongly correlated with root yield and recoverable sucrose (r=-0.8319, P=0.0001 and r=-0.8039, P=0.0001 respectively). LT at the top of the sugarbeet canopy was also correlated with root yield and recoverable sucrose (r=0.9392, P=0.0001 and r=0.9184, P=0.0001 respectively).  The NIR spectral values significantly correlated with root yield and recoverable sucrose (r=0.5405, P=0.0064 and r=0.5728, P=0.0043 respectively) but the relationship was not as strong when compared to either LAI or LT.