Emilia Colucci

The Semi-Minimal-Pruned Hedge: A Novel Mechanized Grapevine Training System

A novel grapevine training system, semi-minimal-pruned hedge (SMPH), designed for mechanized pruning and harvesting was established on Sangiovese. The system was derived from adult spur-pruned cordon (SPC) vines that were modified to form a mechanically pruned hedge. SMPH heights of 80 cm and 120 cm were compared to SPC from 2005 to 2008, with an average of 332 and 479 buds per meter of row on SMPH 80 and 120, respectively, compared to 18 count nodes per meter of row on the hand-pruned SPC. The hedged vines had a larger leaf area, greater leaf area/crop ratio, and 35 to 40% yield increase compared to SPC, but there were no differences in juice soluble solids, pH, and acidity across the treatments. Berry skin anthocyanins were higher in hedged vines, notably the SMPH 120. The SMPH had more numerous but less compact and smaller clusters free of botrytis compared to SPC. While SMPH 120 showed a tendency to alternate bearing, this effect was minimal in SMPH 80. Single-shoot growth measured in 2006 was lower in SMPH vines, and total seasonal canopy light interception was higher compared to SPC vines. SMPH single-leaf assimilation was similar to SPC vines. Mechanical harvesting of both SMPH treatments was successful. These findings suggest that the two SMPH systems warrant further commercial evaluation because of their positive response to mechanization, grape yield, and quality and low susceptibility to bunch rot.

Post-veraison trimming slow down sugar accumulation without modifying phenolic ripening in Sangiovese vines: Post-veraison trimming of Sangiovese vines

BACKGROUND Vineyard strategies have recently been developed to combat the effects of global warming on grapevines, which is causing grapes to ripen quickly, excessive sugar accumulation in berries, and high alcohol levels in wines. We evaluate the effectiveness of post-veraison trimming as a means of slowing down sugar accumulation, without modifying phenolic ripening, in Sangiovese vines grown in highly fertile and well watered soil. RESULTS The removal of about two-thirds of the leaf area by shoot trimming after veraison led to a reduction in sugar content without affecting yield. Total and extractable anthocyanins, skin, and seed tannins showed no significant variation at harvest after the treatment during the three-year trial, while the replenishment of carbohydrates in canes at the end of the trial was negatively affected. CONCLUSIONS These results indicate that, in highly fertile and well-watered soil, post-veraison trimming may represent a powerful tool for decreasing sugar concentration during harvest without affecting yield or total and extractable phenolic compounds. However, the reduction in starch reserves compared to the control serves as a warning about repeated trimming over the years.

The Effectiveness of Basal Shoot Mechanical Leaf Removal at the Onset of Bloom to Control Crop on cv. Sangiovese (V. vinifera L.): Report on a Three-year Trial

Vine basal shoot leaves are known to be the primary nutritional source for fruit set at the onset of bloom. The effectiveness of mechanical removal of this foliage at that date was tested from 2012 to 2014 to control the cropping of high-yielding cv. Sangiovese in a “Toscana rosso” TGI (Typical Geographic Indication) district in Tuscany, where the yield threshold is 16 t/ha. A tractor-mounted leaf remover featuring sideby- side rotary suction and feed rollers was employed along a 50 cm basal area of cropping shoots at the beginning of bloom; control was the usual manual thinning of clusters carried out at veraison in the same vineyard. Mechanical leaf removal eliminated about 30% of leaf area and some shoots and inflorescences, thus reducing cropping potential and even resulting in a physiological effect, as the resulting clusters were composed of lower numbers of berries and were less compact and less susceptible to mould than the control. By harvest, the defoliated vines showed higher leaf area, most likely because leaf removal at the onset of bloom may have triggered compensatory new growth, and their grapes had a higher content of soluble solids than the thinned control. While both treatments kept the yield below the 16 t/ha threshold – leaf removal at an estimated 15.1 t/ha and manual cluster thinning at 15.6 t/ha – mechanical defoliation notably reduced yearly labour input: an estimated 4 h/ha against the 38 h/ha from thinning.