Nonpareil Yields Down - Why?

Reports have came in regarding lower than expected yields on 'Nonpareil,' and higher than expected NOW damage. In the near future, I will discuss some possible reasons for increased NOW damage, but today I will focus on the lower-than-expected 'Nonpareil' yields.

Low bloom densities wereobserved in 'Nonpareil' and othervarieties in the spring of 2012.

Earlier this year, I reported seeing several orchards with a weak return bloom. These orchards leafed out with a full canopy, but had a low bloom/set count. These issues can be over-generalized as a 'hangover' from the 2011 season, but possible explanations included:1. Holding back irrigation in attempts to 'force' hullsplit of the later pollinators, which stressed the trees during the initial fruit bud differentiation period;2. Defoliation due to rust or scab, compounded with a warmer than expected November/December, which led to re-leafing of the trees and loss of potential fruit bud;3. High yields experienced over the past few years that reduced the number of spurs available to support almond development.In elaborating point three, it is important to clarify that almond itself is not considered to be alternate bearing. The spur, on an individual level, however, does alternate bear -- meaning once it produces a nut, the next year it may bloom, but rarely will bear an almond. Since there are a large number of spurs on a mature almond tree, this bearing/non-bearing fluctuation of the spur rarely impacts crop. The exception exists, however, when there are years of high rates of fruit set, in which a larger-than-normal percentage of spurs are setting fruit, reducing the number of spurs for the next year's production (Tombesi, et al, 2011). The implications of this spur bearing pattern may be more severe on developing orchards (years 5-8), as there are fewer spurs available when compared to a mature almond tree.We experienced high rates of nut set within 'Nonpareil' in 2011.Common sense suggests that the problems experienced within this year's yield is not due to one factor, but rather a combination of problems that occurred in 2011. Never-the-less, the drop in yield can serve as a reminder that the orchard management practices applied within a given season affect the current and following year of orchard production.Works Cited: Tombesi, S., B. Lampinen, S. Metcalf, and T. DeJong. 2011. Relationships between spur- and orchard-level fruit bearing in almond (Prunus dulcis). Tree Physiology. Vol.31, pgs 1413-1421.