The Palmette Leader: A Tree Design for Improved Light Distribution

Abstract A tree design, called the “palmette leader”, for improving the distribution of light within the tree canopy is described. The tree is a modification of the common central leader, and is formed by having a complete lower whorl of scaffold branches with a flat north-south-oriented palmette leader above. The large permanent gaps in the upper canopy ensure good light distribution, which was confirmed with canopy transects using fisheye photography. Preliminary evaluations of tree performance with ‘McIntosh’ apples ( Malus domestica Borkh.) indicated that cumulative yields, fruit soluble solids content, and fruit dry matter were greater than well-trained central leaders, but fruit size and fruit color were similar. The improved light penetration into the center of the palmette leader compared to the central leader was found to induce higher photosynthesis of interior spur leaves exposed by summer pruning in August. Management of the palmette leader trees was found to be relatively simple.