SUMMER PRUNING DOES NOT APPEAR TO INCREASE BARTLETT PEAR CROP YIELD ON REDUCED HEIGHT TREES IN NORTHERN CALIFORNIA
This study examined a strategy for maintaining crop yield after reducing the height of tall (6 m) pear trees. Reducing tree height by removing the upper 1–2 m of the tree canopy is likely to remove a substantial percentage of the current bearing surface. We hypothesized that summer pruning following height reduction would stimulate fruitwood production in the lower canopy and allow more rapid recovery of crop yield. The heights of pear trees in two orchards in Lake County, California, were reduced by 2–4 m in 1992 (Quercus Orchard) and 1993 (Thomas Orchard). Summer pruning was carried out in each orchard every June. Summer pruned trees produced 17.5% less crop than non-summer pruned trees in 1995 at Quercus Orchard. A qualitatively similar trend was observed in 1994 at Quercus Orchard and in 1995 at Thomas Orchard. In 1995, the locations and numbers of flowers and fruits in the canopy were determined. Most flowers and fruits were produced in the upper third of the canopy, which also produced the heaviest fruits. Spurs produced more flowers and heavier fruits than terminals. At harvest, no differences in fruit number due to summer pruning were detected at either orchard. Over a period of three years after height reduction, summer pruning caused small increases in flower formation in some canopy locations, but these changes did not result in increased fruit production. This lack of a positive response to summer pruning may have been due to the reduction in carbohydrate availability caused by summer pruning.
Grossman, Yaffa L., Elkins, Rachel B. and DeJong, T. M. (1997). SUMMER PRUNING DOES NOT APPEAR TO INCREASE BARTLETT PEAR CROP YIELD ON REDUCED HEIGHT TREES IN NORTHERN CALIFORNIA. Acta Hortic. 451, 543-550
Pyrus communis, topping, spur fruit, terminal fruit