Growth and Flowering of Vigorous Apple Trees as Affected by Summer or Dormant Pruning1

Abstract

Summer pruning of ‘Starking Delicious’, ‘Golden Delicious’, or ‘Stayman’ apple (Malus domestica Borkh.) trees in mid-August (about 14 weeks after full bloom) did not suppress shoot growth the following year, as compared to similar pruning prior to budbreak in early April. ‘Stayman’ trees pruned in June had more regrowth than those pruned in August. A 1% naphthaleneacetic acid (NAA) solution applied to the summer pruning cut prevented regrowth. The increase in trunk and branch circumference was reduced by August pruning, as compared to dormant pruning. Summer pruning did not influence total bloom the year following treatment, but summer pruning for 2 consecutive years reduced the amount of bloom on 2-yr-wood. Cutting to the first spur on 2-year-wood in August did not suppress shoot growth the following year as compared to heading back to 4 leaves on current season's wood.

Effects of Dormant Pruning, Summer Pruning, Scoring, and Growth Regulators on Growth, Yield, and Fruit Quality of ‘Delicious’ and ‘Cortland’ Apple Trees

“…In contrast, summer pruning consis tently reduced trunk circumference increase of 'Cortland' and of 'Red Prince' the last 2 years. This is in general agreement with Marini and Barden (13,15) and Alderman and Auchter (1). Taylor and Ferree (19) reported that summer pruning most effectively reduced growth of the stem base and roots of pruned trees.…”

“…Summer pruning failed to restrict terminal growth on 'Red Prince' and increased it on 'Cortland' (Tables 1 and 2). These findings and those of others (13,15,17) are in conflict with the suggestion that a major benefit of summer pruning is supression of terminal growth (22). In contrast, summer pruning consis tently reduced trunk circumference increase of 'Cortland' and of 'Red Prince' the last 2 years.…”

“…Much of the photosynthate that is produced late in the season is trans located to the roots (8). Summer pruning can reduce root growth the year treated (15,19), yet can be ineffective in retarding terminal shoot growth the following year (13,15,24). This raises questions about the relative importance of root-delivered photosynthate for shoot growth.…”

Effects of Summer vs. Dormant Pruning and NAA Treatment on Growth of One- and Two-year-old Apple Trees1

“…The reserves are utilized in spring growth until new shoots become photosynthetically self-sufficient (16). We previously found that radial growth of trunks and scaffold limbs was suppressed by August pruning of mature 'Delicious' and 'Golden Delicious' trees the year of treatment (14). Summer pruning in this study significantly suppressed trunk growth the year of treatment, but not the following year.…”

“…In some experiments, summer pruning suppressed shoot growth more the season following treatment than did comparable dor mant pruning (1,2). In other experiments, shoot growth was not suppressed (22) or was stimulated (14) the year following summer pruning in comparison with a similar type of dormant pruning or a nonpruned control (11). At the end of the season, dry weights of roots and stems of young summer-pruned apple trees were less than those of unpruned controls (2 0 ), but data were not presented for growth the year following treatment.…”