Effect of Four Training Systems on Growth and Productivity of `Cortland'/M.9 EMLA Apple Trees

Abstract

`Cortland'/M.9 EMLA trees were planted in 1991 at 1.8 ×4.2-m spacing. The trees were trained to one of four systems: 1) Vertical Axis; 2) Y trellis; 3) Solen; or 4) Palmette trellis. Tree survival was 86% for Palmette trees and approached 100% for the other three systems. Annual yield and cumulative yield per tree of Vertical Axis and Y trellis was twice that of Solen or Palmette. Tree vigor was sub-optimal relative to planting distance in this study. Trunk cross-sectional area of Vertical Axis trees was larger than that of trees trained to Solen or Palmette, while trees trained to Y trellis were intermediate in trunk growth. Canopy volumes of Vertical Axis and Y trellis trees were similar, and greater than that of Solen or Palmette trees. Fruit size on Solen and Palmette trees was larger than that of Y trellis trees in 1995 and 1996, while fruit size on Vertical Axis trees was intermediate. Cumulative yield per cubic meter of canopy volume was the same for all four systems, suggesting that differences in productivity among systems were attributable to the effects of tree training practices on tree size, not to differences among systems in precocity or efficiency. The low heading cut needed to establish the lowest tier of branches on the Palmette system reduced tree vigor and in some cases, resulted in mortality. The horizontal training of the primary branches of the Solen severely reduced tree vigor. In this study, where tree vigor was sub-optimal due to rootstock selection, the additional restrictions in tree growth resulting from restrictive training methods resulted in a significant loss in productivity.