Leaf removal and cluster thinning trials in 'Foglia Tonda' grapevine

The research was carried out in the 2015 growing season in order to optimize the qualitative expression of the native Tuscan 'Foglia Tonda' (Vitis vinifera). The effects of three different treatments for yield control in comparison with the untreated (CTRL) were analyzed: two forms of early leaf removal carried out at the end of May (4 and 6 leaves removed, respectively 4 LR and 6 LR) and cluster thinning (CT) at veraison in August. Investigation in productive activity, qualitative and quantitative grape characteristics were carried out: from veraison to harvest, berry samples were collected and sugar content, titratable acidity, pH, extractable anthocyanins and polyphenols were analyzed. Results showed that 'Foglia Tonda' is a very productive cultivar and therefore is useful to decrease yield excess, with early leaf defoliation or cluster thinning. Overall, early defoliation may be an excellent tool for yield control, replacing time consuming manual cluster thinning.