Submitted to: Journal of American Pomological Society
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/26/2010
Publication Date: 10/1/2010
Citation: Miller, S.S., Scorza, R. 2010. Response of two novel peach tree growth habits to in-row spacing, training system, and pruning: effect on growth and pruning. Journal of American Pomological Society. 64(3):199-217. Interpretive Summary: Most current peach production systems are based on large spreading trees planted at wide spacing. High density systems using dwarfing rootstocks, as in apple, are more efficient and productive, but a proven dwarfing rootstock is not available to peach growers. Compact, upright growing peach canopies would allow for higher density plantings. A planting of narrow canopy peach trees (pillar and upright) developed by the USDA-ARS, AFRS peach breeder was established in 1999 along with standard habit trees to evaluate the performance of these upright canopy trees. After seven growing seasons, pillar trees were the smallest and standard trees were the largest with upright habit trees intermediate, but almost as vigorous as standard habit trees. Both pillar and upright trees appear to be well suited to narrow planting distances (5 to 6.5 feet) within the row. These findings will benefit peach growers, extension fruit specialists, and researchers conducting studies of novel peach tree growth habits.
Technical Abstract: Novel peach tree growth habits, such as the pillar (P) (also called columnar) and upright (UP), offer unique opportunities to develop high-density peach production systems similar to that for apple. This study was initiated to examine the performance of the novel P and UP growth habits compared to a standard (S) peach growth habit when planted at four different within row spacings and trained to a multiple leader (ML) or central leader (CL) system. The effect of summer pruning on all three growth habits was also examined. The three growth habits differed in trunk cross-sectional area (TCSA) after six growing seasons with P trees being smallest and UP next smallest compared to S habit trees. Close spacing (1.5 and 2.0 m) reduced TCSA compared to wider spacing (4.0 and 6.0 m). There was a significant interaction between spacing and growth habit for TCSA and for canopy width. At the close spacings, growth was similar among the three growth habits, but at the wider spacings, the TCSA and canopy width of UP and S trees were similar and much greater than P trees. Summer pruning (SP) annually from the second through the sixth year reduced TCSA and canopy width compared to non-SP trees, but resulted in interactions with spacing and growth habit for terminal shoot growth. The year after SP was discontinued, there were no significant differences in TCSA, canopy width, or terminal shoot growth between SP and non-SP trees. The effects of growth habit and spacing on terminal shoot growth were inconsistent. The P trees required less dormant pruning time and about 50 percent fewer pruning cuts than S trees. The UP trees required about the same time to dormant prune in the seventh season as S trees but required 35 percent fewer pruning cuts/cm-2 TCSA than S trees. The SP reduced the time required for dormant pruning between 28 and 50 percent, depending on year. The difference in dormant pruning time per tree for SP trees was greater for trees spaced at 6.0 m compared to trees spaced at 1.5 and 2.0 m within the row when compared to non-SP trees. Our results show that P and UP growth habit peach trees are well suited to high-density planting systems at spacings of 1.5 to 2.0 m. The results also indicate that these growth habits would benefit from annual summer pruning to aid in reducing growth.