March 9, 2012 7:52am
• New survey shows slightly more oranges per tree
• Very close to average size
Its forecast is based on the results of a survey conducted from Jan. 13 to Feb. 23. Estimated fruit set per tree, fruit diameter, trees per acre, bearing acreage, and oranges per carton were used in the statistical models estimating production.
Measurements and weather conditions are indicating a normal crop year. Cold winter temperatures apparently have not negatively impacted the crop. Survey data indicated an average fruit set per tree of 611, relatively close to the five-year average of 591. The average March 1 diameter was 2.583 inches, very close to the five-year average of 2.585.
Valencia oranges are the kind with seeds. The fruit is usually used in processing and for orange juice.
A Valencia Orange Objective Measurement Survey was conducted from the 1985-86 to 1993-94 seasons before being suspended due to a lack of funding. The survey has been conducted since it was reinstated for the 1999-00 season, with the exception of the 2006-07 season due to a substantial freeze. The data from the first three years after the survey was reinstated were used for research purposes in developing crop-estimating models.
For this year’s survey, a sample of 578 Valencia orange groves was randomly selected proportional to acreage, county, and variety representation for the state, with 533 of these groves being utilized in this survey.
Once a grove was randomly chosen and grower permission was granted, two trees were randomly selected for each grove. For each randomly selected tree, its trunk was measured along with all connected branches. A random number table was then used to select a branch, and then all connected branches from the randomly-selected branch were measured.
This process was repeated until a branch was reached with no significant limbs beyond it. This randomly-selected branch, called the terminal branch, was then closely inspected to count all fruit connected to it, as well as all of the fruit along the path from the trunk to the terminal branch. Since each selected path has a probability of selection associated with it, a probability-based method was then applied to estimate a fruit count for the entire tree.
In the last week of the survey period, fruit diameter measurements were made on the right quadrant of four trees surrounding the two trees of every third sampled grove. These measurements were used to estimate an average fruit diameter per tree. Of the 533 utilized groves, 219 were in Tulare County, 102 were in Kern County, 53 were in San Diego County, 57 were in Ventura County, 34 were in Fresno County, 36 were in Riverside County, 13 were in San Bernardino County, 14 were in Madera County, 2 were in Imperial County, and 3 were in San Luis Obispo County.