Water is the most limiting factor for agricultural production in the semiarid environment of the western Great Plains of the United States.  Dry climate conditions combined with a large availability of ground water has led to crop systems that are dependent on irrigation for maximum yields.  An increased emphasis on water is forcing users to find new ways to increase the efficiency of water used for agriculture.  Crop canopy sensors may have the potential to determine the water status of crops.  If this potential can be realized, an effective, non-invasive way to determine the water requirement of crops rapidly and on a large scale could be developed.  A study was initiated to evaluate the potential of a commercially available crop canopy sensor to effectively relate to crop irrigation level (water applied) at two growth stages where available water is critical after corn tasseling (R3 and R5).  The sensor was used in three distinct orientations to evaluate the effect of the corn tassel on sensor readings and to determine which orientation best determined differences in corn due to irrigation.  The first orientation minimized tassel effect while the other two sensor orientations avoided taking measurements involving the corn tassel entirely. The orientations were 1) nadir, between corn rows (above canopy), 2) 45° off nadir within the corn canopy (below corn tassel), and 3) 90° off nadir within the corn canopy (below the corn tassel).  Two sensor calculated indices (ReNDVI and NDVI) were compared within each sensor orientation at each irrigation level.  Results show that crop canopy sensors can determine differences in corn growth based on irrigation treatment.  The 45° orientation yielded significant positive trends based on irrigation in three out of eight measurements.  The 90° orientation yielded significant positive trends in five out of eight measurements.  The inter-row orientation also yielded significant positive trends in five out of eight measurements.  This suggests that either the 90° or inter-row orientations would work best for the determination of irrigation effects on corn growth.  Overall, the results suggest that crop canopy sensors can distinguish differences in corn growth related to irrigation.  Our results found that a crop canopy sensor could distinguish between different irrigation rates in corn at later growth stages (R3 and R5) when irrigation is usually critical in the semiarid Great Plains.  While more study is needed, this suggests that crop canopy sensors may be a suitable tool for increasing water use efficiency.