PRUNING AND REGENERATION OF THE ROOT SYSTEM ON PEAR AND APPLE TREES

In Fall 1985, a root pruning experiment was established in a 16-year-old ‘Bartlett’ (Vilamovka) pear orchard. The trees were propagated on seedling rootstock and planted in a palmette system at a spacing of 4.5 x 3.5 m. The orchard floor was maintained by clean cultivation without irrigation. Root pruning by chisel was performed at a depth of 35 cm and a distance of 2.0 m from the tree. The experiment was prepared with two treatments: root pruning on one side or both sides of the tree row. The control was maintained with a standard tillage of 20-cm depth. Before and during the experiment, the root system was analyzed as to the quantity and types of roots removed and regeneration of the root system. The experiment continued for 3 years. Root pruning on one side of the tree row resulted in the highest yield: an increase of 11.7% in the third year (average 18.4%). Two-sided root pruning increased the yield by only 2.8%, but the fruit were largest. The average yield of the control plot was 46.8 tons/ha.

A similar experiment (1988–90) was performed on 17-year-old apple trees, and the roots were pruned at a depth of 60 to 70 cm. Yields increased 20% in the first year, 77% in the second year, and 5% in the third year. In order to control vegetative growth, yield and fruit quality, results indicated that the most successful root pruning should be applied only to one side of the tree during the first 2 years and to the other side in the third year.