Groundbreaking research shows that high productivity
can be maintained and there is enough sunlight for crop
drying when 80% of sunlight at midday is intercepted
and 20% reaches the orchard floor, as seen here.
Ongoing research by UCCE farm advisor Roger Duncan in Stanislaus County confirms past research in almond-growing regions throughout California: There are many reasons to prune an almond orchard, but yield does not appear to be one of them. The 37-acre trial has also shown that traditional tree spacing of 22 feet by 22 feet or more is probably too far apart to intercept the sunlight necessary to optimize production in most orchards.
New orchards should be designed to maximize light interception through minimal pruning and training, proper rootstock selection and optimum spacing to enhance yield while avoiding orchard management problems, Duncan says.
Since 1999, Duncan’s trial has looked at various pruning and training strategies for Nonpareil and Carmel on Nemaguard and Hansen 536 (peach-almond hybrid) rootstock combinations. The goal is to find an orchard spacing configuration and pruning/training technique that produce the most benefit in yield potential and profitability without creating problems related to crop drying, limb breakage, orchard diseases and worker safety.
Research by UCCE almond specialist Bruce Lampinen on midday light interception — also supported through the Almond Board’s Production Research program — has examined various rates of light interception and their impacts on yield, nut quality, disease and orchard profitability. Lampinen concludes that 80% light interception is a good target. Both of these trials have produced groundbreaking results.
This is a summary of an article that was published in Western Farm Press, July 21, 2012, page 14, and online July 5. See the full article for links to the latest results from the 2011 season and detailed data from this trial.