Desert grapefruit pruning and orchard thinning trials

Pulling alternate trees and pruning to increase the amount of sunlight available to each tree failed to increase per-acre yield or grower returns over a four-year period in a red grapefruit grove near Coachella. The grove was planted in 1956 on fertile soil at a spacing of 13.5 × 24 ft with the expectation that alternate trees would be thinned out when the grove began to be crowded. The grower originally planned to inter-plant trees on rough lemon alternated with trees on Cleopatra mandarin. The trees on rough lemon were expected to give high early production and to be eliminated at thinning time, allowing the Cleopatra mandarin trees to remain for the permanent orchard. By 1967 when the plot work was undertaken, no trees had been pulled, and the grove was overcrowded and too shady.