John Edstrom conducts the CE pomology/tree crops programs in Colusa and has cross-county responsibilities for CE almond programs in Sutter and Yuba Counties. John has been on the Colusa CE staff since 1984. He graduated from CSU, Chico, with a Masters Degree in Plant Science, emphasizing pomology. Previous work experience included ten years of commercial orchard advising and research.

The major crop responsibilities include almonds, walnuts and prunes. There is additional interest in wine grapes and pistachios. Collectively, tree crops were produced on over 31,000 acres in Colusa County in 1997, with an on-farm value of in-excess of $68 million. This was about twenty percent of the total county ag income.

The following are major issues or trends facing the Colusa tree crop industries:

Applied Research Activities

John conducts a significant portion of his extension program at the Leslie Nickels Soil Laboratory (NSL) facility in Arbuckle. This facility is a Trust for research related to soil and/or water issues. It is administered by three trustees, including the Colusa CE County Director. All of the 20 current research projects being conducted at Nickels have UC faculty as Principal Investigators. It is a "self-sufficient" operation, which only receives modest support from the University or County.

The income from the approximately 70 acres of bearing almonds supports the research occurring there. There are another 20 acres of non-bearing almonds planted, as well as modest acres of walnuts and prunes.

A unique cooperative funding arrangement between Colusa County, the California Almond Board and the Nickels Trustees provides a full-time field assistant to manage the facility and coordinate the research projects.

UC research was initiated at Nickels in the 1970's and information developed there has been of immense value for increasing the grower returns to Colusa County orchardists. Development of drip irrigation technology, almond variety/rootstock information, hedgerow production systems and non-chemical approaches to important insect pests are acknowledged as originating at Nickels. It is an important asset to the county’s tree crops industries.

Future plans include establishing additional research plantings on the remaining 110 acres of currently fallow ground included in the estate.

Specific current pomology research projects include:

1- A prune planting that has challenged conventional thinking about prune production on marginal soils. Yields of 4-5 tons per acre (twice the state average) of premium large sized fruit have been obtained from test plots.

2- Evaluation and identification of "safer" pesticides for insect and disease problems. The industry has been quick to adopt these technologies.

3- Began new trial to evaluate the feasibility of reducing pruning costs on almonds, while increasing early production.

4- Colusa County became a participant in an Almond Pest Management Alliance program, funded by Cal DPR, to demonstrate low insecticide/fertilizer production systems and encourage growers to minimize the risk of negative environmental effects from almond farming.

5- An evaluation of hedgerow walnut production that has led to increased local production of walnuts on marginal soils. This technology is being widely adopted by growers and is partially responsible for the expanded plantings on the Westside.

6- Further investigations and refinements of micro-irrigation of almonds, including sub-surface drip, which led to reductions in the amount of herbicides and irrigation water required for optimum almond production. This project is receiving primary funding from national and international funding agencies.

7- Major rootstock investigations, including a California hybrid rootstock trial funded by the California Almond Board and nursery industry.

8-     A new orchard design tested at Nickels appears to hold the promise of lessening the need for high numbers of honeybees to pollinate almonds. Results show that the concept of planting two alternating varieties down the same row can increase pollination/yield, compared to the current practice of having solid rows of a single variety. ‘ Mission’ and ‘Padre’ varieties were the primary varieties tested and others need to be evaluated. The potential savings in pollination costs or the ability to stretch limited beehives over expanding acreage will benefit growers.

9-     Self-fertile almond variety development to minimize planting multiple varieties in each orchard and lessen dependence on bees as primary pollinators.

10-   A test evaluating beneficial insect releases for control of walnut worm pests. This test is being conducted with a commercial grower off the Nickels site.

11-    Potassium fertilizer injected via micro-sprinklers at NSL, after two seasons, does not indicate economic benefits for almond yield or quality. This test is ongoing and the results are tentative.

Send mail to jlschmierer@ucdavis.edu with questions or comments about this web site.
Copyright © 1999 Colusa County Cooperative Extension, Univ. of California
Last modified: September 01, 2000