Franz Niederholzer, UCCE Farm Advisor, Colusa and Sutter/Yuba Counties

In 2025, prune bloom was late with a very hot spike in temperature around full bloom.  This led to concern for a very light fruit set across all orchards (crop failure). Fortunately, five weeks after full bloom, the fruit set looks to be generally good across the Sacramento Valley. Fruit set counts in orchards from Sutter to Tehama Counites are generally very good (20-40% set). These are good fruit set numbers, but a light bloom in some orchards has contributed to a variable crop picture from orchard to orchard around the valley. However, overall, it looks like there’s a good chance for a decent prune crop this year in the Sacramento Valley. 

Results from this spring support the following statements:

• Early blooming years (full bloom before March 15-16) have higher risk of weather-related poor fruit set than those with later bloom (after March 16).
• A good prune fruit set can be expected when full bloom is late (after March 21).

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Maximum daily temperatures and timing of prune bloom (0-100% open flowers = green box), from south (Verona CIMIS station) to north (South Gerber CIMIS station) Sacramento Valley, 2025.