Worm pressure — primarily, navel orangeworm and secondarily, peach twig borer — varies by region, according to Duncan, but the relative tolerance-susceptibility ranking of different varieties is stable and is dependent on both shell seal and hull split/harvest timing in relation to insect flights.

One source of data supporting these conclusions is the RVT plots, particularly the Kern County 1993–2006 trial. Another resource is the industry-wide percent inedible (reject) data published by the Almond Board. A five-year (2006–2010) recap ranking rejects of the top varieties and Winters is available through the Varieties page accessed by the link near the end of this article. This recap parallels the RVT observations and research, and the data shows Nonpareil is susceptible to worm damage, while a number of key varieties sustain less damage, and some varieties, such as Sonora, have somewhat more damage than Nonpareil.

Kernel quality                 

The RVT reports also have data on percent double kernels and twins (two kernels within the same pellicle). The data should be assessed over a number of years to look for a consistent trend within a variety, such as is found with doubling occurrence in Monterey. Even so, as Roger Duncan noted, it is important to check with your handler to determine if doubling and twins are important factors in light of applications such as dicing or consumer end uses such as in-shell.

“Fit” for farming operation and style

Farm advisor Duncan explained how operation size can impact decisions on the mix of varieties.  Growers farming several hundred acres may want to spread out cultural operations, such as bloom sprays and harvest. Small growers may want to minimize the number of varieties, grow varieties that can be harvested within a short time frame and either mixed together or kept separately, or grow what a neighbor has in order to share equipment. These bloom and harvest considerations were covered in the second article of this series, which can be found online at www.farmpress.com/tree-nuts.

Lastly, variety choice may be a matter of style. Are you a risk taker? As Duncan pointed out, there are plenty of new promising varieties: Sweetheart, Avalon, Durango, Folsom, Independence, Kochi, Marcona and Supareil. For several of these, there are no long-term data spanning both a number of years and locations. Nevertheless, you may want to diversify your “risk portfolio” by trying out a new variety, which may turn out a winner. In doing so, almond breeder Tom Gradziel noted, you may experience the “Tiger Woods Effect,” in which no matter how promising a new variety is, it is performance over the life of an orchard that makes money. Connell concluded by saying the final test is if, after 20 years’ experience, you would choose to replant with that same variety.

For information on almond varieties, including the complete conference panel presentations and reports from the Regional Variety Trials sponsored by the Almond Board, go to AlmondBoard.com/farmpress22.  Another valuable resource is the chapter “Evaluation and Selection of Current Varieties” in the Almond Production Manual (UC Division of Agriculture and Natural Resources, Publication 3364, published in 1996).