Training and Performance of Pillar, Upright, and Standard Form Peach Trees – Early Results

Peach production in the U.S. relies on standard size trees on vigorous, seedling rootstocks grown at low-densities (≤ 297 trees/ha). Production per hectare is low. Peach tree growth habits, such as pillar (P) (columnar canopy shape) and upright (U), can be planted in high-density systems with the potential for increased production per hectare. Pillar and upright, advanced breeding selections, and standard (S) (‘Harrow Beauty’) trees on ‘Lovell’ rootstock were planted at 4 densities (135 trees/ha to 1112 trees/ha) and trained to a central leader (CL) or multiple leader (ML) form. Trees were dormant pruned and trained, then summer pruned (SP) in the first growing season after fall planting. One-half of the trees were SP in the second growing season after dormant pruning. Growth habit affected trunk and canopy size after two growing seasons. SP reduced canopy spread. Dormant CL training after one growing season required more time than ML training for all growth habits, however, the difference was greater for U and P trees (110% more time) than for S trees (39%). Branch spreading with training aids contributed to the greater training time for CL trees. Summer pruning increased light levels in the lower canopy with the greatest effect in S and U trees. Yields in the second leaf were greater for ML trained trees than CL trees. SP reduced the yield of U trees but not S or P trees. Based on these data and observations of U and P peach trees growing on a deep, well-drained fertile site, it appears that pruning and training of P and U trees to conform to a specific form may result in excessive tree vigor. Reduced early training to allow for expression of the natural growth habit may be preferable. INTRODUCTION Commercial peach [Prunus persica (L.) Batsch] production is based on standard size trees budded on vigorous, seedling rootstocks grown in low-density [≤ 297 trees/ha (120 t/acre)] systems. In recent years, fruit researchers and growers have used various training and pruning techniques to conform these standard growth habit trees to several high density planting systems (Bargioni et al., 1985; Chalmers et al., 1978; DeJong et al., 1994; Erez, 1982; Hayden and Emerson, 1988). An alternative approach to high density is the development of growth habits suited to high-density systems (Scorza, 1984). Two growth habits with the most potential for high density planting are the pillar and upright form trees (Scorza, 1988). Performance tests of peach tree growth habits, in general, have been conducted and published (Bargioni et al., 1985; Bassi et al., 1994), but large-scale evaluations for pillar and upright trees at several planting densities and with different training methods have not been conducted to-date in the United States. This is a preliminary report of observations and findings on the pruning and training of pillar and upright peach trees growing at several planting densities at the USDA Appalachian Fruit Research Station (AFRS), Kearneysville, WV.