North Sac Valley: Jaime Ott, UCCE Tehama, Shasta, Glenn, Butte Counties 

Despite a much earlier bloom than last year, harvest started only a few days earlier. Fruit size and sugar at harvest was variable: blocks with heavy cropload or which suffered from water stress during the season struggled with size and sugar. Tonnage was down this year overall, mainly driven by losses to sunburn (blue prune drop) during our hot weather. Some orchards were nearly unaffected, while others suffered heavy losses. The most heavily affected orchards I saw were on drip irrigation. In previous years, data from temperature sensors has shown that drip-irrigated orchards run 5-10°F warmer in hot weather than sprinkler or micro-sprinkler orchards, which might help to explain the pattern. Not every drip-irrigated orchard suffered from high levels of sunburn, though, so there is more to the story than just in-orchard air temperature. I saw firsthand the importance of using a sizing chain to get rid of sunburned fruit: in some bins of harvested fruit, almost half was nothing more than a pit with some dried skin around it. This was a tough year for mites, with many growers spraying multiple times through the season. That could also be related to the hot, dry weather we had.    

South Sac Valley: Franz Niederholzer, UCCE, Colusa, Sutter, Yuba Counties 

In Sutter County, the season started out looking “normal”. Chilling (74 chill portions by March 1) and full bloom timing (March 20-23) were right about recent averages. Bloom temperatures were not dangerous to fruit set, peaking at just under 80 deg (a high of 79oF on Mar 19). Fruit set numbers were generally good with more than 30% of flowers setting fruit in orchards where bloom was tracked around the county. That level of fruit set along with a decent to good bloom usually means fruit thinning should be needed to attain good fruit size in most orchards.   

Spring weather was the usual temperature yo-yo in a wet spring with ±25oF swings in maximum daily temperatures from late March into early Mary. However, storm temperatures were cold (max temps <60oF), which probably helped reduce disease (fruit brown rot and rust) pressure. The post bloom heat units, measured as cumulative Growing Degree Hours 30 days after bloom (GDH30) for Sutter Co in 2024 were on the cool side…6094, suggesting a slightly longer growing year and larger sizing potential. Reference date was May 10.  

Any sense this was an “average season” went out the window in early July. Summer 2024 was one of the hottest in the last 20 years, producing fruit sunburn, web spinning mite outbreaks, and lower sugars heading into harvest. Sunburn from July heat caused significant fruit loss (< 20% of total crop) across the region. The easing of temperatures later in August likely helped sugars increase heading into harvest. Many growers delayed harvest as they waited for sugar levels to increase, particularly in orchards with excessive croploads. Overall, processors report a good crop with reasonable size.