NAA THINNING OF ´JONAGOLD/M.9´ APPLES IN RELATION TO SPRAY VOLUME, DOSE AND SPRAY DEPOSITION IN THE CROWN

M. Stopar, A. Simoncic, G. Leskosek
A study was conducted in an apple orchard on dwarf rootstock (3000 trees/ha) to determine the required water volume and appropriate dose of naphthaleneacetic acid (NAA) per hectare which would provide the best spray distribution and thinning in different parts of the tree crown. Run-off spraying was compared to lower water volumes from 2000 liters (L) to 250 L/ha applied by an axial fan sprayer. Fruit thinning effect was estimated by considering the fruit number and weight at harvest or the return bloom in the following season. When NAA 10 mgL-1 was sprayed using 1500 L of water per hectare the thinning was found to be effective and this rate/spray volume was determined to serve as the recommended dose rate of NAA per hectare for this kind of orchard. If the 1500 L of water was reduced to 1/2, 1/3 or 1/8 of the standard volume while the NAA dose/ha remained constant, the same thinning effect was observed as with the original 1500 L water volume spraying. When NAA 10 mgL-1 whole tree application (with 1500 L/ha) was compared to spraying only the upper half of the tree (750 L/ha or 500 L/ha) unsuccessful thinning in the upper and in the lower half of the crown was found in the case of partial treatment. If NAA 10 mgL-1 was sprayed to the upper half of the crown with 1000 L/ha separately, adequate thinning was observed in the whole tree.
Stopar, M., Simoncic, A. and Leskosek, G. (2006). NAA THINNING OF ´JONAGOLD/M.9´ APPLES IN RELATION TO SPRAY VOLUME, DOSE AND SPRAY DEPOSITION IN THE CROWN. Acta Hortic. 727, 445-450
DOI: 10.17660/ActaHortic.2006.727.54
https://doi.org/10.17660/ActaHortic.2006.727.54
apple thinning, NAA naphthaleneacetic acid, water volume, spray distribution
English

Acta Horticulturae