THE EFFECT OF HANDTHINNING ON YIELD AND RETURN BLOOM OF FIVE PEAR CULTIVARS IN A NORTHERN CLIMATE

Preliminary results from an experiment of fruit thinning by hand on the five pear cultivars ‘Keiserinne’, ‘Clara Frijs’, ‘Amanlis’, ‘Moltke’ and ‘Philip’ are reported.
The objectives were to decide time and degree of thinning to achieve high annual yields and high fruit quality.
The timing of the treatments extended from pink bud to the stage of fruitlets, 10 and 20 mm in diameter.
The thinning degrees were one king flower/fruit per (a) one cluster, (b) two clusters, (c) three clusters and (d) four clusters.
The experiment was conducted on mature trees, spaced 3 × 5 m, trained as free spindle and limited to 2.5 m height over a period of three years.
Annual data of flower numbers, yield and fruit quality were recorded.
In average for the period and all cultivars thinning at pink bud reduced the yield to about 30% of the control trees.
The yield of the control varied from 30 kg per tree for ‘Moltke’ to 14 kg for ‘Clara Frijs’ in average for the three years.
Thinning at 10 and 20 mm fruit diameter reduced the yield to about 2/3 of the control trees.
No yield difference was obtained between the two treatments.
The yield became reduced linearly with increasing degree of thinning.
Thinning to one fruit per cluster at 10 or 20 mm fruit diameter gave the most uniform yields.
Thinning increased return bloom significantly for ‘Clara Frijs’, ‘Amanlis’ and ‘Moltke’, less for the two other cultivars.
Prolonged period of thinning reduced the fruit size and the sugar content all cultivars.

VII International Symposium on Pear Growing

M. Meland

Handthinning, yield, fruit size, soluble solids, return bloom, Pyrus communis L.

https://doi.org/10.17660/ActaHortic.1998.475.33