The initial 2017-18 Navel orange forecast for California is set at 70 million cartons, the lowest level seen since 2008-9. Of the total Navel orange forecast, 68.0 million cartons are estimated to be in the Central Valley.
This forecast is based on the results of the 2017-18 Navel Orange Objective Measurement (O.M.) Survey, which was conducted from July 8 to September 1, 2017.
Estimated fruit set per tree, fruit diameter, trees per acre, bearing acreage, and oranges per box were used in the statistical models estimating production. The varieties forecast in this report include conventional, organic, and specialty Navel oranges (including Cara Cara and Blood orange varieties).
Survey data indicated a fruit set per tree of 273, below the five-year
average of 348. The average September 1 diameter was 2.341 inches,
above the five-year average of 2.240 inches.
Survey Sample
A sample of 576 Navel orange groves was randomly selected
proportional to county and variety bearing acreage, and 540 of the
groves were utilized in the survey. Once a grove was randomly chosen
and grower permission was granted, two trees were randomly selected.
The Navel orange sample included organic, Cara Cara, and Blood
orange groves.
Of the 540 utilized groves, 8 were in Madera County, 89 were in Fresno County, 315 were in Tulare County, and 128 were in Kern County.
A Navel Orange Objective Measurement Survey has been conducted in
the Central Valley every year since the 1984-85 crop year, except for
the 1991-92 season due to a lack of funding. The data from the first two
years were used for research purposes in developing crop-estimating
models.
Source: nass.usda.gov