SOME FACTORS AFFECTING FRUIT SET OF THE PACKHAM’S TRIUMPH PEAR

Packham’s Triumph is self incompatible.
Young and old trees often set unsatisfactorily despite a heavy blossom and normal provision for cross pollination.
This is not due to a short effective pollination period nor to poor development of placental tissue of ovules.
Artificial supplementary pollination with viable compatible pollen and a fall or spring application of 2, 4, 5-trichloro phenoxy propionic acid can only partly overcome the problem.
Other synthetic growth substances are ineffective.

Competition between shoot and fruit in young vigorously growing trees and competition between fruit and fruit in older spur bound trees are important factors determining final fruit set in some pear varieties.
This competition presumebly results in embryo abortion followed by fruit drop.

The adverse effects of competition can be overcome by pruning.
In young vigorously growing trees the competitive effects can be reduced by judicious removal of strong one-year-old shoots in winter and removal of growing points of bourse shoots shortly after full bloom.
Similar results were obtained in old spur bound trees by heavy spur pruning in winter to reduce the number of fruit buds.

III International Symposium on Pear Growing

H.J. van Zyl, D.K. Strydom

https://doi.org/10.17660/ActaHortic.1982.124.19