INTRODUCTION

  Since the processing industry began to utilize the large majority of the orange crop in Florida, the concept of production estimates and forecasts only in terms of boxes of a given weight no longer fully reflects the statistical needs of the citrus industry. To be more meaningful, forecasts and estimates of production need to be expressed in terms of total pounds of solids as well as in terms of boxes. This publication provides a summary of results from randomly sampled fruit collected and tested by the Florida Agricultural Statistics Service for recent years.

HISTORY OF CITRUS MATURITY TESTING PROGRAM

  In the late 1950's the Service began to collect fruit samples of oranges monthly to determine if maturity and yield factors could be projected in advance of harvest. For several years field personnel picked a single fruit from each grove they entered to make monthly counts and size measurements in their regular drop and growth surveys. These fruit were combined into a single sample for each type of orange--early, midseason, and late--then juice was extracted with the aid of an electrically operated reamer. The necessary weights and test results were accumulated. Within a few seasons, it was determined that declines in acid, increases in soluble solids and solids-to-acid ratios and, later in the season, decreases in juice and gains in pounds solids followed predictable patterns. It appeared from these data that changes in these elements could be predicted over time if sufficient observations were available to provide a valid statistical base. None of the results of these tests were published. The yields of pounds solids shown in these tests appeared to be correlated with changes in yield levels of fruit received at the processing plants.

  In early 1963, following the disastrous freeze of December 1962, the industry was very concerned over the level of pounds-solids yield that would be obtained from Valencia oranges which had been damaged severely. In response to recommendations by the Citrus Crop Estimates Advisory Committee and requests from others in the citrus industry, the Florida Agricultural Statistics Service conducted a series of tests using fruit from randomly selected sample groves. Three successive tests were made at two week intervals. These tests indicated rather accurately the abnormally low levels of juice and pounds of solids in Valencias that spring.

  This pilot project provided experience for developing regular survey procedures which would yield statistically reliable results. Sufficient funds were available to finance the work and a regular program of monthly surveys began on October 1, 1963. The sample size selected in these first surveys provided for 50 groves each for early, midseason, and late oranges. Reports were issued individually on early and midseason oranges on the first of each month from October through January in the 1963-64 season, and from October 1 through February 1 in the 1964-65 and 1965-66 seasons. Valencia orange test results were reported on October 1 through April 1 in the 1963-64 season, and through May 1 in the 1964-65 season. In the 1965-66 season, Valencias were tested at the first of each month from October through February and, beginning in February, a midmonth report was added, continuing through April of that season. In the 1966-67 season, testing began September 1 and midmonth tests were added to the previous monthly programs.

  In 1967, following a statistical evaluation of the preceding four years' results, the Service responded to industry requests for area data from the maturity and yield tests, and expanded sample sizes. In that year, the number of early orange groves was established at 73, midseasons at 55, and Valencias at 100. September 1 continued as the first test date and the schedule of midmonth tests was retained.

  In the 1964-65 season, seedless grapefruit tests were added to the program with a separate series for white and colored varieties. A series for seedy grapefruit was added in the 1965-66 season and retained through the 1983 season, but has been discontinued because of steadily declining production.