Articles
THE EFFECT OF BLOSSOM DESICCANTS ON CROP LOAD OF PACKHAM¿S TRIUMPH PEAR
Article number
596_125
Pages
729 – 733
Language
English
Abstract
Trials have been conducted over a two year period to assess the potential of blossom desiccants as chemical thinning agents for the pear cultivar Packhams Triumph.
Replicated small plot field trials were established on a commercial orchard at Nubeena in Tasmania.
Initial trials examined four rates of the desiccant ammonium thiosulphate (Culminate™) (0.5%, 1.0%, 1.5%, 2.0% v/v) at three different timings during the flowering period (20%, 50%, 80% bloom). Higher concentrations of Culminate resulted in greater reductions in crop load at application timings of 20% or 50% bloom.
There was little thinning effect in any of the 80% bloom treatments, irrespective of concentration.
There was no effect on return bloom.
Further work examined the effect of double and triple applications of Culminate during the flowering period.
Two applications of 1.0% or 1.3% Culminate reduced crop load but three applications of 0.7% were required to have a thinning effect.
Adding the post-bloom thinner CyLex™ to the thinning program had no additional thinning effect.
Culminate has proved to be an effective thinner of Packhams Triumph. Both concentration and time of application of this chemical are critical in achieving a satisfactory level of thinning without causing excessive phytotoxicity to the tree.
To thin effectively Culminate needs to be applied as early as the 20% bloom stage.
Follow up with a second application from 50% bloom is likely to enhance the thinning effect.
Once full bloom has been reached it is too late to apply desiccants.
Replicated small plot field trials were established on a commercial orchard at Nubeena in Tasmania.
Initial trials examined four rates of the desiccant ammonium thiosulphate (Culminate™) (0.5%, 1.0%, 1.5%, 2.0% v/v) at three different timings during the flowering period (20%, 50%, 80% bloom). Higher concentrations of Culminate resulted in greater reductions in crop load at application timings of 20% or 50% bloom.
There was little thinning effect in any of the 80% bloom treatments, irrespective of concentration.
There was no effect on return bloom.
Further work examined the effect of double and triple applications of Culminate during the flowering period.
Two applications of 1.0% or 1.3% Culminate reduced crop load but three applications of 0.7% were required to have a thinning effect.
Adding the post-bloom thinner CyLex™ to the thinning program had no additional thinning effect.
Culminate has proved to be an effective thinner of Packhams Triumph. Both concentration and time of application of this chemical are critical in achieving a satisfactory level of thinning without causing excessive phytotoxicity to the tree.
To thin effectively Culminate needs to be applied as early as the 20% bloom stage.
Follow up with a second application from 50% bloom is likely to enhance the thinning effect.
Once full bloom has been reached it is too late to apply desiccants.
Publication
Authors
S.A. Bound, L. Mitchell
Keywords
ammonium thiosulphate, Culminate, thinning, Pyrus communis, fruit set
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