EFFECTS OF SUMMER PRUNING ON YIELD, FRUIT SIZE, AND FRUIT QUALITY OF THE APPLE CULTIVAR ‘SUMMERRED’

Late-summer pruning of ‘Summerred’ apple trees for four consecutive years had no effect on yield and fruit size. Red color development on fruit, especially from the interior of the canopy, improved significantly. A lighter ground color of apples from summer-pruned trees was obtained. The content of soluble solids was reduced by summer pruning, but no consistent effect on fruit acidity could be found. Under Norwegian growing conditions at latitude 60° north, summer pruning may be carried out during the second half of August. Summer pruning is recommended in orchards where light penetration of the internal part of the canopy is insufficient for adequate development of red color to meet the standards required for high-quality apples.