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Ultrasonic sensors can be used to estimate tree canopy volume variability within groves, which is useful for planning site-specific management practices and estimating crop yield. The objective of this study was to investigate the errors in tree canopy volume measured with a 10-transducer ultrasonic orchard measurement array and Trimble AgGPS 132 DGPS. Sensitivity analysis was used to investigate the magnitude of errors in ultrasonically-sensed tree canopy volume measurement (EUCV) caused by several factors including ground speed accuracy measured by DGPS, uncalibrated air temperature, ultrasonic transducers, deviation in driving path from the centerline between two rows. The height error in the transducer array due to tire inflation and uneven ground was also calculated. Canopy volume of a selected tree was measured with the ultrasonic system and used as the basis to calculate EUCV caused by the parameters. One hundred data points were generated within the selected range of each parameter to calculate EUCV and the ranges were determined on the basis of measured data and literature. The EUCV increased as the ground speed increased and the error in volume was 6.78% for the speed range of 1.30.088 m/s. The EUCV was 4.83% for the temperature range of 5-45C. The ultrasonic transducer error component in canopy volume measurements was 2.29%. The EUCV due to deviation in path from the centerline between two tree rows was 1.56%. The height error due to uneven ground and wheel tracks ranged from 0.025 to 0.12 m. These results could be used to control error in ultrasonically-sensed canopy volumes for accurate site-specific application of agrochemicals within orchards.