"Sunburn is a major issue in apple production, resulting up to 40% yield loss (Schrader et al., 2006). ... For several years, the fruit surface temperature (FST) has been used as a reliable indicator of the sunburn susceptibility (Rackso and Schrader, 2012). Several contact type instruments, e.g., thermocouples, thermal probes, etc. have been used to measure FST. However, these methods can be inaccurate, data-limited, destructive, and laborious (Wang et al., 2020). Therefore, our research group has developed and validated a field-deployable, crop physiology sensing system (CPSS) prototype for accurate and real-time apple FST estimation."