Multiple entries have covered the aspects of ensuring irrigation during the post-harvest period. This practice has been based off of previously conducted research and is recommended due to the detrimental effect that post-harvest water stress has on the following year’s crop. Never-the-less, many growers do not recognize the importance of this practice.
An irrigation stress or deficit during the post-harvest period has been shown to reduce bloom, fruit set, fruit load, and individual fruit weight. For example, a University of California study conducted between 1989-1990 that deprived trees of post-harvest irrigation resulted in a 10% reduction in fruit set, a 33% reduction in fruit load, and a 43.3% decrease in kernel yields for the nonpareil variety*. It is thought that the sensitivity of the almond to the lack of post-harvest irrigation is most likely due to the late fruit bud differentiation which occurs from late August to early September.
As the first “round” of harvesting is completed, keep in mind the need to irrigate the trees. It is easily forgotten with the hustle and bustle of harvest, but the potential consequences of forgetting should turn the practice into a priority.
*Research paper cited: Goldhamer, D.A., Viveros, M. 2000. “Effects of preharvest irrigation cutoff durations and postharvest water deprivation on almond tree performance.” Irrigation Science. Vol 19: 125-131.