Techniques to modify cluster architecture and their effect on the viticultural performance of the Sauvignon Blanc cultivar

Alberto Fontanella Brighenti,Douglas André Würz,Jerônimo Vieira De Araújo Filho,Mateus Da Silveira Pasa,Aparecido Lima Da Silva,Bruno Munhoz,Felipe Augusto Moretti Ferreira Pinto

doi:10.1590/s1678-3921.pab2020.v55.01900

Abstract

Abstract: The objective of this work was to evaluate the effect of different techniques to modify grape cluster architecture on the incidence and severity of botrytis bunch rot, as well as on the viticultural performance of the 'Sauvignon Blanc' grapevine (Vitis vinifera). Associated with fungicides, four treatments were tested: control, 30 ppm gibberellic acid sprayed at full bloom, 1,000 ppm prohexadione calcium sprayed at full bloom, and berry thinning at the stage of beginning of berry touch. The experiment was carried out in the 2015, 2016, and 2017 vintages. Clusters were treated with fungicides during the stages of full bloom, beginning of berry touch, veraison, and around 15 days before harvest. Berry thinning does not cause losses in the yield and quality of 'Sauvignon Blanc', and, despite having little effect on cluster architecture, is effective in reducing the incidence and severity of Botrytis cinerea. Prohexadione calcium improves grape phenolic maturation, is effective in reducing the incidence and severity of B. cinerea, and reduces cluster compactness by decreasing berry diameter. The application of gibberellic acid spray at full bloom is not recommended because it decreases yield and bud fertility and increases berry susceptibility to B. cinerea infection.

Highlights

In the last decade, the highlands of the state of Santa Catarina, in Southern Brazil, have stood out as a region for the production of high-quality wines (Würz et al, 2018)
The objective of this work was to evaluate the effect of different techniques to modify grape cluster architecture on the incidence and severity of botrytis bunch rot, as well as on the viticultural performance of the 'Sauvignon Blanc' grapevine
The treatments consisted of: 30 ppm gibberellic acid sprayed at full bloom; 1,000 ppm prohexadione calcium (ProCa) sprayed at full bloom; berry thinning at the phenological stage of beginning of berry touch; and control, plots only treated with the fungicides

Summary

Introduction

The highlands of the state of Santa Catarina, in Southern Brazil, have stood out as a region for the production of high-quality wines (Würz et al, 2018). Botrytis bunch rot or gray mold, caused by the fungi Botryotinia fuckeliana (de Bary) Whetzel and Botrytis cinerea Persoon ex Fries in conidial form, is one of the most important grape diseases in the highland regions of Southern Brazil (Bem et al, 2017). This disease is a problem in regions with cool and wet macroclimates, and, in general, fungal infection is most likely to occur when clusters are dense and little exposed to the sun (Hed et al, 2009; Mundy et al, 2014)

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