Luke Milliron, UCCE Orchards Advisor, Butte, Glenn, Tehama Counties

2025 Observations at Bloom: 

My former colleague Dani Lightle wisely noted that what stands out in the early years of a variety trial is not what looks good – it’s what looks bad. For the new UC almond variety trial planted spring 2023, testing nearly 30 varieties from all over the world, four varieties are already on the chopping block for early removal from the trial (Figure 1). UC Davis B3 is a small, self-sterile tree showing extensive bud failure, while self-fertile UCD B8 has very few flower buds. Both varieties also tested positive for viruses. Lassen and P10.023 both from Burchell Nursery, are a fraction of the size of Nonpareil. Both varieties are performing decently at the other two locations on Hansen 536 rootstock, therefore the problem could be a partial incompatibility with Krymsk 86 rootstock. All four varieties are being considered for removal in early spring 2025, to be replanted with other varieties for testing. 

Other Observations: 

Shasta on Viking: These 3rd leaf trees in the 2023 planted trial look good so far. They had good bloom density (4 out of 5 visual rating) entering their 3rd leaf at the Butte and Kern sites in a year with widespread reports statewide of very poor bloom density for the Shasta variety (Figure 2). However, they had poor bloom density (2 out of 5) at the Modesto sister site, following a heavy crop in that orchard’s second leaf last year. I am investigating if a high percentage nut set leads to alternate bearing for this variety. The jury is still out on whether 14 feet down the row with Viking rootstock on excellent ground is tight enough spacing (Figure 3). 

Yorizane on Krymsk 86:  As the Yorizane on Krymsk enter their 12th leaf in the older variety trial, it appears that either the 18 feet down the row spacing would have to be tightened or the tree would need to placed on a higher vigor rootstock to better compete with Nonpareil yields (Figure 2). However, at 3rd leaf in the newer trial at 14 feet down the row, Krymsk 86 rooted Yorizane so far looks like a good spacing at this site (Figure 3). Despite 11 years of data on this variety at the three 2014 planted variety trial sites, we will learn much more about this variety, including its flaws as it gets planted out by growers.

Independence on Viking: These trees had good bloom density in 2025 as they entered their 3rd leaf. Unfortunately, 14 ft down the row Independence on Viking rootstock in excellent soil – does not appear to be tight enough/high enough vigor rootstock to achieve full yield potential (Figure 3). 

Making tree buying decisions? Feel free to call for my 2 cents: Luke Milliron (530) 828-9666.

Figure 1. Varieties being considered for early removal: UCD B3 (upper left), UCD B8 (upper right), Lassen (lower left), and P10.023 (lower right). Photos show these trees as they enter their third leaf in February and March of 2025 at the CSU, Chico Farm. Photos by Luke Milliron.

Figure 2. Yorizane and Nonpareil both Krymsk 86 rootstock entering their 12th leaf (left). Shasta on Viking (3rd leaf, right) with good bloom density in 2025. Photos by Luke Milliron on February 17, 2025.

Figure 3. Comparison of tree canopy filling a 14-foot middle for Shasta on Viking (top), Yorizane on Krymsk 86 (middle), and Independence on Viking (bottom) at the start of the 3rd leaf (3/19/2025). Photos by Luke Milliron.