Among the earliest and most important decisions a grower will make when replanting an almond orchard is the selection of rootstocks and compatible varieties.
Rootstock selection, and corresponding decisions about compatible and desirable varieties, is a complicated process. The first step is to select a rootstock based on conditions at a specific site, including chemical and physical properties of the soil, nematode pressures, disease pathogens and problems with anchorage or drainage.
From there, growers can make the important decisions about variety compatibility with those specific rootstocks.
In many cases, according to UC Farm Advisor Joe Connell in Butte County, the rootstock/scion decision is driven less by what will help solve a problem than it is by knowing what rootstocks to avoid that can aggravate a problem or that won’t survive in a given situation.
The bottom line is that growers must look at the complexity of issues at the site when replanting almond orchards, and then find the rootstock and compatible variety that will thrive best under the given set of conditions.
The Almond Board of California (ABC) has funded rootstock research for 25 years, including field evaluation trials dating back to 1988. ABC is currently funding three new trials in Merced, Yolo and Butte Counties, in addition to several ongoing trials. It has also leveraged farm bill block grant funds to set the course for more focused and long-term assessment and development of rootstocks to provide resistance to soilborne diseases and nematodes.
For more information, see the Almond Board–funded project “Field Evaluation of Almond Rootstocks” at AlmondBoard.com/ResearchReports
. Select all the key categories (Annual Reports, Updates/Proceedings, Posters) of Almond Board–funded research, and search for projects 08.HORT4.Duncan, 09.HORT4.Duncan and 10.HORT4.Duncan.
This article, by the Almond Board’s Bob Curtis and Gabriele Ludwig, is a summary of the second in a series of articles on orchard replanting published in Western Farm Press. The complete article is in the April 16 issue, pages 16–17, and online at westernfarmpress.com