California Walnut Objective Measurement Report

Dan Commodity Report, Tree, nut & vine crops

walnutsRecord Walnut Production Forecast

The 2014 California walnut production is forecast at a record 545,000 tons, up 11 percent from 2013’s production of 492,000 tons. This forecast is based on the 2014 Walnut Objective Measurement (O.M.) Survey, officially conducted by the National Agricultural Statistics Service August 1 through August 22, 2014. There were a few samples completed before August 1 for training and scheduling purposes.

Despite a lack of chilling hours and a drought that has hit California, the 2014 walnut crop is forecast at a record level. Growers used surface water where available and groundwater when necessary to provide adequate water supply to the trees. Weather conditions during the growing season were mild thus benefitting the crop. Crop quality is excellent with low disease and insect pressures. Overall, the 2014 crop is developing faster than last year and harvest is expected to start early.

The 2014 Walnut O.M. Survey utilized a total of 746 blocks with two sample trees per block. Survey data indicated an average nut set of 1,372 per tree, up 11 percent from 2013’s record low average of 1,239. Percent of sound kernels in-shell was 98.7 percent Statewide. In-shell weight per nut was 21.2 grams, and the average in shell suture measurement was 32.5 millimeters. The in-shell cross-width measurement was 32.4 and the average length in-shell was 38.1 millimeters. All of the sizing measurements were above average levels.

Estimated nut sets, sizing measurements, average number of trees per acre, and estimated bearing acreage were used in the statistical models.

Survey History

The Walnut O.M. Survey began in 1958 to fulfill industry needs for an accurate walnut production forecast prior to harvest. The original sample was chosen proportionally to county and variety of bearing acreage. With each succeeding year, additions and deletions have been made in the sample to adjust for acreage removed, new bearing acreage, and operations that choose not to participate in the survey.

Sampling Procedures

Once a block is randomly selected and permission is granted by the operation for enumerators to enter the block, two trees are randomly selected. An accessible branch is chosen, which is 5-15 percent of the total cross-sectional area of the primary limbs and reachable with a twelve-foot ladder. Measurements are made on the trunk, each primary, and each split leading to and including the accessible branch. The sample tree and accessible branch are marked by a single tag.

On the accessible branch, every first of five nuts is picked for use in size and grade determinations. If available, at least ten nuts are harvested from the accessible branch for this purpose.

The following measurements are made on nuts selected for sizing:

1. Weight of nut including hull
2. Width of shell at suture
3. Width of shell 90 degrees to suture line (cross-suture)
4. Length of shell
5. Kernel grade
6. Weight of nut in-shell

Data Reliability

The 80 percent confidence interval is from 501,000 tons to 589,000 tons.

View the full USDA California Walnut Objective Measurement Report. (.pdf)