Regional Testing of Almond Varieties Ongoing - yield results through 2020
Roger Duncan, UCCE Pomology Farm Advisor, Stanislaus County
In 2014, UC Cooperative Extension planted identical almond variety trials in three major growing areas of the Central Valley. The Butte, Stanislaus, and Madera County trials were planted on Krymsk 86, Nemaguard, and Hansen 536 rootstocks, respectively, at tree densities of 110, 130, and 173 trees per acre. These trials feature 30 selections from the UC Davis and USDA breeding programs and several commercial varieties from California nurseries. Twelve of the varieties are self- fertile, meaning they can be planted in a solid block, require fewer bees, and have one harvest. Varieties are being compared side by side in one field under commercial farming conditions. Experimental varieties are planted like pollinizers, every other row with Nonpareil rows in between. Information including bloom time, hull split, harvest time, yield, kernel quality, and insect & disease susceptibility are recorded for each variety.
After several years of intensive data collection, a few new varieties and selections are showing promise. An experimental pollinizer variety from UC Davis, currently called UCD 18-20, and the pollinizer variety Booth from Burchell Nursery, are top-yielding varieties across all three locations to date. UCD 18-20 blooms with Nonpareil, shakes well and harvests about a month after Nonpareil. Booth also shakes well and harvests 10-20 days after Nonpareil, depending on soil and rootstock. USDA varieties Yorizane and Y117-91-03 are self-fertile and are also high yielding, with Y117-91-03 being the highest yielding variety in the Stanislaus trial. We expect this experimental variety to be released by the USDA soon. Yorizane, a small tree with high kernel quality, was released in 2020 and is becoming available from many commercial nurseries. A few other varieties in the trials have excellent kernel quality but only moderate yields so far.
Cumulative yields for the first five years of harvest are shown in the table below, as well as tree canopy size (measured as PAR – the higher the PAR, the larger the canopy). We assume small canopied varieties with high yield efficiency could be planted closer for higher yields per acre. For instance, experimental variety UCD 8-160 is a very small tree but yields better than all other varieties in the trial for its size. It is important to realize that juvenile yields may not reflect long-term yields as canopies continue to develop. Some varieties, including UCD 18-20, have a high percentage of doubles or other problems which may limit their adoption. Although some varieties are performing well so far, we suggest longer-term study is prudent before risk-averse growers choose to plant any new variety.
A more complete report of this study can be found at our website cestanislaus.ucdavis.edu or in the Almond Board’s database at almondboard.com. We are currently planning a new set of regional variety trials to be planted in 2023. It will include many more self- fertile varieties from California and overseas.
