Submitted to: Society of America Plant Growth Regulator Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 3, 2002
Publication Date: N/A
Interpretive Summary: Fruit tree size is managed to enable high density plantings that simplify cultural and harvest activities in the orchard. Management of tree size and excess vegetative growth is a significant expense to orchardists and accurate information is needed regarding the biological effects and efficacy of cultural practices used to manage growth. Scoring is a circumscribing cut around a tree trunk, made by orchardists to manage fruit tree size and to improve yield. However, scoring has variable effects on vegetative growth, possibly due to imprecision that is inherent in cutting a tree with a saw blade or knife. In this experiment, we substituted for scoring by restricting trunk diameter enlargement with a steel band encircling the tree trunk and tightened to a specified tension. The goal was to more precisely control trunk disruption and, therefore, be an improved technique for controlling vegetative growth. We measured the effects of trunk scoring and trunk restriction on growth, photosynthesis, and leaf sugar levels in apple and peach trees. Results demonstrated that banding disrupted the physiology of both apple and peach trees by interfering with photosynthesis, carbohydrate partitioning, and possibly hormone transport, but this altered physiology did not consistently affect growth during the season of treatment. Banding may be a useful tool for the study of root/shoot communications within fruit trees but, as applied in this experiment, banding did not appear to have practical use for controlling shoot growth during the season of application. In contrast, scoring reduced shoot growth of apple trees during the first season but not the second season after treatment. Scoring reduced peach growth the second season after treatment. Thus, scoring appeared to have greater practical application for shoot growth control in apple than peach.
Technical Abstract: Scoring tree trunks has been used to manage fruit tree growth, but response to scoring has varied, possibly due to imprecision of cutting a tree with a saw blade or knife. Restricting trunk diameter enlargement with a band tightened to a specified tension could allow more precise trunk restriction for controlling vegetative growth. An experiment was conducted to compare the effects of scoring with banding of tree trunks on growth and yield in apple and peach trees. Apple (Malus domestica Borkh.) and peach (Prunus persica (L.) Batsch) trees were planted together near Kearneysville, WV in April 1997. In May 2000, three treatments were installed 20 cm above the graft union: (1) the trunk was cut to the secondary xylem in a double spiral pattern that did not girdle the trunk (score); (2) the trunk was completely encircled by a hose clamp to 11 kg-cm which was removed in Aug. (band); and (3) untreated control. In April 2001, four treatments were installed 20 cm above the graft union of different trees than those used in 2000: (1) score as described above; (2 and 3) band as described above but tightened to 28 kg-cm and 57 kg-cm; and (4) untreated control. In 2000 scoring suppressed growth of peach early in the growing season and growth of apple for the entire season. Banding did not significantly suppress shoot growth in either species but it reduced photosynthesis and altered carbohydrate partitioning. Results in 2001 were similar to that obtained during the 2000 growing season; scoring reduced apple but not peach tree growth and banding did not reduce growth in apple or peach. In 2001, banding increased yield per tree and soluble solids in apple fruit. It appeared that banding disrupted the physiology of both apple and peach trees by interfering with photosynthesis and carbohydrate partitioning but this altered physiology did not affect growth during the season of treatment. Scoring reduced shoot growth of apple trees during the first season but not the second season after treatment.