Impact of tree removal on the yield and manual harvesting of Florida orange trees

Stephen H. Futch, T. Adair Wheaton, Jodie D. Whitney


Since the 1960s, high density citrus plantings have produced more fruit early in the grove's life with quicker returns on investment than groves with standard tree densities. Fruit yields in high density groves may decline, however, after trees reach containment size. In a closely spaced citrus grove in Manatee County, Fla., 9- to 10-year-old trees of 'Hamlin' on Carrizo citrange and 'Valencia' on Swingle citrumelo rootstocks were sheared at 0.3 m (1 ft) above the ground to reduce tree density and to determine the effects of tree removal (thinning) on yield, fruit quality, tree growth, and manual harvesting rate. The study consisted of 3 treatments: unthinned hedgerow, and removal of every second or third tree in the plot area. Unthinned trees were in two-row beds at 7.3 m (24 ft) between rows and 2.4 m (8 ft) in-row providing 560 trees per ha (227 trees per acre). Tree density was reduced to 279 and 373 trees per ha (113 and 151 trees per acre) by the two removal rates. For both varieties, yields were significantly reduced with decreased tree density. Harvesting efficiency of hand labor increased with tree removal because of the increased open space. Tree growth, as measured by trunk circumference, was greater for both varieties with decreasing tree density. During the 6-year study period, high density hedgerows provided highest cumulative yields with annual differences between treatments decreasing with time.


Citrus sinensis; 'Hamlin; ' 'Valencia; ' planting densities; tree thinning; high density plantings; harvesting efficiency; boxes per man-hour

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283