A method for assessing frost damage risk in sweet cherry orchards of South Patagonia

Quantification of frost damage risk is important in planning the development of new orchard areas and for decision-making on design and installation of frost control systems. The objective of this study was to develop a comprehensive method to quantify frost damage risk in different sweet cherry production areas of South Patagonia and to estimate the potential impact of frost control systems on risk reduction. Lack of historical weather data required a theoretical-empirical approach. Frost damage for any specific day of the season was assumed to occur when the minimum temperature on that day was below the specific lethal temperature for the phenological stage predicted at that moment (based on phenological models). Frost damage probability was estimated for each production location of South Patagonia as the frequency of seasons in which at least one damaging frost (damaging 90% of the reproductive organs) occurs, at any time during the growing season until harvest. Frost damage risk was compared among cultivars and locations. Finally, the effect of active frost control methods on frost damage risk reduction was analyzed. There was very little difference in frost damage risk among cultivars, although 'Sunburst' was the cultivar with the lowest risk. The most risky locations were Los Antiguos and Esquel, while Comodoro Rivadavia was the safest location. The frequency of years with at least one killing frost decreased dramatically when the minimum temperature was increased by 3 °C, using active frost control systems. The methodology presented appears useful to identify the main and secondary variables affecting frost damage risk. Thus, this type of quantitative analysis can support growers in decision-making on required investments and operational costs of the equipment for frost control, on the basis of potential impact of a particular control system on mean yields and yield stability. It may also be a guide to prioritise research issues to fill knowledge-gaps with regard to frost risk assessment