Peach Fruit Growth Prediction

Research from California shows that peach fruit growth, including harvest date and final fruit size are related to weather conditions for the first 30 days after bloom (Lopez and DeJong, 2008), measured in growing degree hours (GDD-30). When weather conditions in the first 30 days are substantially warmer than normal (GDH higher than 6100), fruit harvest is earlier, but the fruit size potential is reduced. Under these conditions, early and extensive fruit thinning is suggested to optimize fruit size. When weather conditions are cooler than normal (GDH-30 is lower than 6100), then harvest is later and fruit size is larger. Note: this relationship has not been verified under Utah conditions.