Nitrogen Level and Time of Mechanized Summer Shearing Influence Long-term Performance of a High-density ‘Redskin’ Peach Orchard

Abstract ‘Redskin’ peach ( Prunus persica Batsch.) trees, planted at a high-density spacing (3 × 5 m), were fertilized annually with urea at rates of 45, 90, or 135 kg·ha −1 . Trees were trained to a trapezoidal hedge by annual, mechanized, summer pruning. Within each fertilizer plot, subplots of five summer-pruning treatments were applied. Single pruning treatments were made at 120 days after full bloom (DAFB) and 150 DAFB. Paired pruning treatments were applied 30 + 60 DAFB, 60 + 120 DAFB, and 60 + 150 DAFB. Pruning at 120 DAFB alone, and in combination with pruning at 60 DAFB, decreased trunk cross-sectional area (TCA), fruit soluble solids content, and weight, while increasing the percentage of surface that was red. Pruning at 30 DAFB followed by a second pruning at 60 DAFB decreased leaf Ca concentration in comparison to pruning treatments applied later in the season. Increasing N fertilization also decreased leaf Ca. Year, N level, and pruning treatments gave a statistical interaction on mean fruit weight and yield.