Sep 8, 2021
Forecast for California walnut production down 15%

The 2021 California walnut production is forecast at 670,000 tons, down 15% from 2020‘s record production of 785,000 tons. The forecast is based on 385,000 bearing acres, up 1% from  2020’s estimated bearing acreage of 380,000.

Widespread freezing temperatures in late fall of 2020 resulted in  frost damage to walnut orchards across the state. Growers reported the frost damage delayed leaf out and reduced nut set in affected orchards. Additionally, because of the state’s drought conditions, orchards experienced a higher degree of freeze injury. Walnut growers throughout the state struggled with drought conditions and water availability, as most of the state is in a drought emergency. Chilling hours were up from last year.

Survey data indicated an average nut set per tree of 992, down 17% from 2020s average of 1,197. Percent of sound kernels inshell was 99.5% statewide. Inshell weight per nut was 22.2 grams, while the average inshell suture measurement was 32.4 millimeters. The inshell crosswidth measurement was 33.4 and the average length inshell was 37.9 millimeters.

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

The 2021 Walnut Objective Measurement (O.M.) Survey was officially conducted from July 25 through August 26, 2021. There were a few samples completed before July 25th for training and scheduling purposes. There were 1,402 trees sampled from 701 orchards.

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 515% of the total crosssectional area of the primary limbs and reachable with a 12foot 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, so that the same trees are sampled the following year if that orchard is selected. On the accessible branch, every nut is counted and the first of every 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 (crosssuture)

4. Length of shell

5. Kernel grade

6. Weight of nut inshell

The Objective Measurement Survey is funded by the California
Walnut Board.

The full report can be read here.

– USDA-NASS 2021 California Walnut Objective Measurement Report

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