EFFECT OF THINNERS ON YIELD, FRUIT SIZE AND RIPENING TIME OF HIGHBUSH BLUEBERRY

Thinning of highbush blueberry with 1 % ammonium thiosulfate (ATS), 1.5 % fatty amine polymer as ArmoThin, 200 ppm 6-benzyladenine (BA), and 10 or 20 PPM N-(2-chloro-4-pyridyl)-N-phenyl urea (CPPU) was applied on the varieties ‘Rancocas’ and ‘Elliott’. ATS and ArmoThin were sprayed at full bloom while the synthetic cytokinins BA and CPPU were applied two weeks after bloom.
Because of too high concentrations of all four thinners, flowers, fruits, shoots and leaves were injured.
Consequently, the highest yield was achieved with the control while the 1% ATS, 1.5% ArmoThin and 200 PPM BA reduced the yield by half on both cultivars.
The strongest reduction in fruit was observed for the ArmoThin and BA applications.
High concentrations of CPPU also caused late fruiting.
The peak ripening time of ‘Elliott’ treated with CPPU 10 or 20 ppm was three or six weeks later than that of the control.
With ‘Rancocas’ the effect of CPPU on ripening time was not as significant.
In a second trial we treated the varieties ‘Bluecrop’ and ‘Elliott’ with 20 and 50 ppm BA and and 5 ppm CPPU at the end of bloom.
No effect on total yield was observed.
CPPU at 5 ppm increased the size of ‘Elliott’ fruit.
In low concentrations CPPU did not prolong the ripening time of either variety.

VIII International Symposium on Vaccinium Culture

D. Koron, M. Stopar

Vaccinium corymbosum, ATS, ArmoThin, BA, CPPU

https://doi.org/10.17660/ActaHortic.2006.715.39