Peach systems trial: The influence of training system, tree density, rootstock, irrigation and fertility on growth and yield of young trees in South Carolina

The purpose of this trial is to compare conventional South Carolina (SC) peach [Prunus persica (L.) Batsch] tree culture with higher levels of management for short and long-term impacts on tree growth, yield, cost of production and profitability. In 1999, the research orchard was established consisting of three tree training systems and planting densities: i. Open Center (5.5 m x 5.5 m spacing - 332 trees/ha); ii. Quad V (5.5 m x 2.7 m spacing - 664 trees/ha); and iii. Perpendicular V (5.5 m x 1.8 m spacing - 997 trees/ha); two rootstocks: i. `Lovely; and ii. 'Guardian(TM)'; and three irrigation/fertilization treatments: i. Rainfall only plus granular fertilization at standard commercial recommended rate (standard); ii. Supplemental irrigation plus granular fertilization at standard rate; and iii. Supplemental irrigation plus liquid fertilization (fertigation) at a reduced rate compared to the standard. The scion cultivar is `Redglobe'. During the first three years of the trial, supplemental irrigation substantially increased trunk cross sectional area (TCA) relative to the nonirrigated treatment. This is primarily due to the lack of sufficient summer and spring rainfall during 1999-2001: No disadvantage was observed when trees were fertilized at a reduced rate compared with the standard. By 2001, high and medium density trees became more crowded in the tree row and as tree density increased, TCA was reduced. Three radiational frost events in 2001 dramatically reduced marketable tree yield (yield) for the shorter open center trees in comparison with the taller quad V and perpendicular V trees. As a result, yield of quad V and perpendicular V trees was 4-5 fold greater than open center trees. Yield for supplementally irrigated trees was double that of nonirrigated trees. In 2002, yield was greatest for open center trees. This was due, in part, to insufficient summer pruning in the V trees resulting in shading out of fruiting wood. For trees receiving supplemental irrigation, yield was approximately 3040 percent higher and percent loss was substantially reduced in comparison with nonirrigated trees.