Declining yields in oranges: Appraisal of 220 mature orange orchards in five counties indicates possible causes of downward trend in production

Abstract Not Available – First paragraph follows: Average production of southern California oranges dropped from 370 to 265 field boxes per acre—for navels—and from 290 to 265 field boxes per acre—for Valencias—over a 12-year period. Many individual orchards in Los Angeles, San Bernardino, and Orange counties—the three areas most seriously affected—showed a production decline of as much as 100 to 250 field boxes per acre during the same period.