Temperate fruit trees require chilling for rest completion, followed by sufficient heat accumulation for onset of growth and bloom. The application of phenological models to predict bloom dates has been widely used in orchard management. Examples of such application include selecting adapted cultivars less prone to early bloom, predicting needs for frost protection, and preventing damage from late spring freezes. This study merged the Utah (chill) and ASYMCUR (forcing) phenological models by combining chill units and heat units (measured in growing degree hours) to predict bloom dates of tart cherries (Prunus cerasus L.) in Utah and Michigan, the top producing states of the USA. It was found that the modified Utah model improves the estimation of chill units compared with the original one, while the original Utah model may still be suitable for use in the colder winter of Michigan (with its later bloom dates than Utah). The combined models were applied with the temperature predicted by the Climate Forecast System v2 (CFSv2) model. The prediction was applied twice a month, starting from 1 February to 1 May. The Utah-ASYMCUR model using the forecasted temperature from CFSv2 exhibits subseasonal performance in predicting the bloom dates for 6 weeks in advance. The prediction can offer growers a way to mitigate extreme climate anomalies.

中文翻译：

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美国犹他州和密歇根州酸樱桃开花日期的亚季节预测：将物候模型与 CFSv2 预测合并

温带果树需要冷却才能完成休息，然后积累足够的热量以开始生长和开花。应用物候模型预测开花日期已广泛应用于果园管理。这种应用的例子包括选择不太容易早花的适应性栽培品种，预测防冻需求，以及防止晚春冻结造成的损害。这项研究通过结合寒冷单位和热量单位（以生长时间测量）合并了犹他州（寒冷）和 ASYMCUR（强迫）物候模型，以预测犹他州和密歇根州的酸樱桃（Prunus cerasus L.）的开花日期，这是产量最高的美国各州。结果发现，与原始模型相比，修改后的犹他州模型改进了对冷量单位的估计，而原始的犹他州模型可能仍然适用于密歇根州较冷的冬天（其开花日期比犹他州晚）。组合模型应用于气候预测系统 v2 (CFSv2) 模型预测的温度。从 2 月 1 日到 5 月 1 日，该预测每月应用两次。使用来自 CFSv2 的预测温度的 Utah-ASYMCUR 模型在提前 6 周预测开花日期方面表现出亚季节性能。该预测可以为种植者提供一种缓解极端气候异常的方法。使用来自 CFSv2 的预测温度的 Utah-ASYMCUR 模型在提前 6 周预测开花日期方面表现出亚季节性能。该预测可以为种植者提供一种缓解极端气候异常的方法。使用来自 CFSv2 的预测温度的 Utah-ASYMCUR 模型在提前 6 周预测开花日期方面表现出亚季节性能。该预测可以为种植者提供一种缓解极端气候异常的方法。