Selecting varieties is a complicated task. There is no perfect choice, yet the decision is one that growers must live with for a long time. At the 2009 Almond Industry Conference, a panel of experts gave growers assistance in this choice by reviewing variety development, evaluation and selection, while balancing both field and market considerations. This second article looks at the "checklist" of issues to consider when choosing almond varieties in terms of bloom, pollination and harvest timing.
As a rule, the better the variety-bloom overlap, the
better opportunity for cross-pollination. This
photo represents poor bloom overlap. Photo by Joe
Almond varieties are grouped by approximate peak-bloom periods, based on days before or after peak Nonpareil bloom. They are classified as Early, Early-mid, Mid-late, Late-mid, Late and Very late. An updated listing of varieties in each bloom group is included in farm advisor Joe Connell’s presentation. (See link to all presentations in last paragraph.)
As a rule, the better the variety-bloom overlap, the better opportunity for cross-pollination. It is best to choose varieties in the same group or adjacent groups, recommends farm advisor Roger Duncan in his presentation. Good bloom options for Nonpareil also include those in the mid groups. Other options are those that have a peak bloom just before or after Nonpareil peak. Duncan added that to maximize yield potential, it is best to have two pollinizer varieties in addition to the main variety, such as Nonpareil, for a total of three. Smaller operations that rely on custom harvesting may want to consider just two varieties: the main variety and a pollinizer.
Another bloom consideration is the order of bloom time between varieties. A variety that blooms early will inherently have a higher set than a later-bloom variety. For instance, if Nonpareil is the main variety, then a variety that blooms just ahead of or at the same time as the Nonpareil peak is much better than a variety that blooms later.
Almond varieties fall into specific groups within which cross-pollination will not occur. It is very important to check which variety combinations are incompatible. An updated list of the pollen-incompatible groups is included in Connell’s presentation.
There is heightened interest in recently introduced self-compatible and partially self-compatible varieties. Although self-compatible varieties will reduce reliance on bees, it will not eliminate them.
According to Connell, in essence, when a variety reaches 100% hullsplit, the nuts are harvestable. In his presentation, he reviewed a table showing 100% hullsplit of different varieties categorized and grouped by the number of days before or after Nonpareil hullsplit.
In commenting about harvest, Duncan noted that some varieties, like Fritz and Monterey, harvest late, potentially exposing the crop to rain damage and possibly precluding the planting of these varieties in some areas. In addition, some varieties like Sonora and Price may harvest too soon after Nonpareil; therefore, it may be difficult to put on a postharvest irrigation for Nonpareil, especially in flood or solid-set-sprinkler-irrigated orchards, until after the pollinizers are also harvested.
This article, by the Almond Board’s Bob Curtis, is a summary of the second in a series of articles on choosing almond varieties published in Western Farm Press. The complete article is in the Sept. 17 issue, page 14, and online (dated Aug. 19) at westernfarmpress.com/tree-nuts. Information on almond varieties, including the complete conference panel presentations and reports from the Regional Variety Trials (RVT) sponsored over the years by the Almond Board, can be found at the Almond Board website.