TECHNICAL AND ECONOMIC PRACTICABILITY OF CHEMICAL THINNING OF ‘FUJI’ APPLES IN THE STATE OF SANTA CATARINA, SOUTH BRAZIL

The performance of NAA, NAAm and carbaryl in single applications and in combination sprays was evaluated in thinning trials at Fraiburgo/Santa Catarina during the growing seasons 1985/86 and 1986/87. Each chemical treatment contained either a common wetting agent or an emulsifiable mineral oil as an adjuvant.
The selection of the most appropriate treatments for commercial use was based on economic analyses.
Early applications of NAA within 10 days after full bloom gave higher mean fruit weights than later applications at 15 days after full bloom.
The use of mineral oil instead of wetting agent as an adjuvant notably improved the thinning effect of NAA, NAAm and the NAA-carbaryl combination spray.
Most chemical treatments were economically superior to hand thinning.
NAA at 15 mg 1^-1 and NAAm at 80 mg l^-1 applied with mineral oil as an adjuvant at 10 and 5 days after full bloom, respectively, provided adequate thinning and were of interest from an economic point of view.
In orchards with very high initial fruit set it is recommended NAA at 15 mg l^-1 together with mineral oil be applied at 5 days after full bloom.
This treatment gave the greatest thinning in both years of observation.

International Workshop on Apple Culture in the Tropics and Subtropics

A. Ebert, C.L. Kreuz

https://doi.org/10.17660/ActaHortic.1988.232.18