Temperature is used to predict lethal temperatures for sweet cherry buds, but it can differ from the actual bud tissue temperature. We compared different types of sensors to quantify bud tissue temperature in 2022 and 2023 spring seasons. A significant difference between air and bud tissue temperature was observed during spring frost nights. Bud tissue temperature dropped rapidly below 32°F compared to air temperature. The relationship between air and bud tissue temperature could be used to better predict lethal temperatures.
Spring Frost Management
Sweet cherry production is challenged by frost damage particularly in the early spring. In 2022-23 season, the net fruit yield across Washington State was reduced by 21% due to cold injury in the late winter and early spring seasons (USDA NASS, 2022). As buds develop in the early spring, they deacclimate to cold temperatures. Occasional warmer temperatures in early spring can expedite the onset of bud break making them more susceptible to frost damage from subsequent colder temperatures. Therefore, knowing the critical temperature in which sweet cherry buds are killed is vital for timely active frost mitigation like heaters and wind machines. Cold hardiness models use air temperature as a predictor to forecast the cultivar-specific critical temperatures. However, crop tissues exhibit a unique heat-holding capacity that can affect the tissue temperature during clear sky nights or direct exposure to daylight (Millar, 1972; Landsberg et al., 1974; Snyder et al., 2005). Thus, using air temperature may lead to inaccuracies in predicting critical temperatures and resulting in premature or delayed actuation of active frost mitigation. We conducted a series of experiments to better understand the relationship between air and bud tissue temperature as well as sensors to measure them.
