CHEMICAL THINNING OF PEACHES

The benefits of flower or/and fruits thinning have been demonstrated through long years of experiences (over four decades) : high constant yields of high qualities fruits. There were tried different thinning methods: hand (5), chemical (1, 2, 3, 4, 5, 6, 7, 8, 9) and mechanical (2, 7, 8, 11, 15) the last two being completed by an additional hand thinning, when necessary.

Because of the high labor costs and late time of hand thinning operation (after June fruit drop) and the uneven distribution of fruits in the canopy after shaking, enhancing of cancer and fuel consumption in mechanical thinning method, all the efforts were directed to the finding out of a chemical which thins effectively the flowers or fruitlets of peach tree. Many chemicals have been tested: auxins, DNOC, morphactines, ethylene generators, but no chemical as yet is fully satisfactory because of the multitude of internal and external factors which affect the efficacy of thinning.

During 1977–1983 several trials were carried out at Fruit Research Stations Constantza and Bucuresti-Baneasa, in order to find out a chemical(s) which thins peaches under Romanian ecological conditions.

There were taken into account the up to-date knowledge about time of application of different chemicals (3, 4, 10, 13, 17) and the thinning effects (2, 12, 15).