hull rot, anthracnose, Alternaria
leaf blight and scab were observed in RVTs following
wet springs. Photo credits: Jack Kelly Clark, University of
California Statewide IPM Program, and Joe Connell,
Butte County farm advisor.
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, balancing both field and market considerations. This article reviews variety characteristics for disease and insect susceptibility, kernel quality and “fit” for your farming operation and style.
New results are available from the Regional Variety Trials (RVT) funded by the Almond Board and other sources. For instance, Nonpareil is among the more tolerant varieties to Alternaria, rather than being very susceptible. An updated version of the RVT findings can be found at the link mentioned in the last paragraph.
In addition to these findings, farm advisor Joe Connell, Butte County, has found the RVT plots valuable for identifying newer test varieties that are highly susceptible to certain diseases that are “bad standouts” during wet years such as occur during an “El Niño.” These observations are included in Connell’s presentation, which can also be found by following the link at the end of this article.
An additional finding is that Winters, a partially self-compatible variety, is very susceptible to anthracnose, Alternaria and scab and may not be appropriate for southern plantings where Alternaria is a persistent problem.
Worm pressure — primarily, navel orangeworm and secondarily, peach twig borer — varies by region, 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.
Data from RVT also 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.
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.
“Fit” for farming operation and style
Farm advisor Roger Duncan, Stanislaus County, 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.
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. Connell concluded by saying the final test is if, after 20 years’ experience, you would choose to replant with that same variety.
This article, by the Almond Board’s Bob Curtis, is a summary of the third and final in a series of articles on choosing almond varieties published in Western Farm Press. The complete article is in the Oct. 22 issue, page 16, and online (dated Oct. 24) 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.
Other articles in this series:
Selecting Varieties Is a Complicated Task for Almond Growers
Bloom, Pollination and Harvest Timing