Experience in thinning trial to regulate the fruit load on three apple cultivars

The regulation of the fruit load is a fundamental practice to obtain quality productions for both commercial and organoleptic characteristics. In addition to this, the regulation of the fruit load through the thinning of flowers and fruits allows to maintain constant and regular crop through the years, avoiding the phenomenon of bi-annual bearing, with undoubted advantages also in the development of vegetation-plant production. For the integrated productions, different molecules are available for the thinning of the fruits, but besides the chemical thinning it is possible to use brushing machines for flower control. The most common is the Darwin model, which works with a rotating central rotor on which are applied plastic wires with the function of tearing flowers. In addition to this model, a prototype machine for mechanical thinning (Florix) has been developed and produced by a local company. During spring 2021, a thinning test was conducted at the Mach Foundation’s experimental farm where a chemical thinning strategy was compared to the mechanical thinning and one untreated plot. The different theses were applied on three cultivars of apple, ‘Gala’, ‘Golden’ and ‘Fuji’, and to assess the effect of the interventions, percentage of fruit set was calculated on selected fruit-bearing branches. Twelve plants for each thesis were then harvested individually and the production was calibrated in the same way. The results have shown a significant effect of the different strategies in relation to the untreated control, both on the production per plant and on the number and size of the fruits for the different cultivars.